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Dorji K, Klungthong C, Dorji T, Wangchuk T, Yuden P, Pelki T, Ghishing TD, Gyemiry G, Gyeltshen S, Chinnawirotpisan P, Manasatienkij W, Wangchuk S, Farmer A. Epidemiology and genetic characterization of influenza viruses circulating in Bhutan in 2022. PLoS One 2024; 19:e0304849. [PMID: 39288111 PMCID: PMC11407632 DOI: 10.1371/journal.pone.0304849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 05/21/2024] [Indexed: 09/19/2024] Open
Abstract
INTRODUCTION Influenza (Flu) causes considerable morbidity and mortality globally, and in Bhutan, Flu viruses are a leading cause of acute respiratory infection and cause outbreaks during Flu seasons. In this study, we aim to analyze the epidemiology and the genetic characterization of Flu viruses circulated in Bhutan in 2022. METHOD Respiratory specimens were collected from patients who meet the case definition for influenza-like illness (ILI) and severe acute respiratory infection (SARI) from sentinel sites. Specimens were tested for Flu and SARS-CoV-2 viruses by RT-PCR using the Multiplex Assay. Selected positive specimens were utilized for Flu viral genome sequencing by next-generation sequencing. Descriptive analysis was performed on patient demographics to see the proportion of Flu-associated ILI and SARI. All data were analyzed using Epi Info7 and QGIS 3.16 software. RESULT A weekly average of 16.2 ILI cases per 1000 outpatient visits and 18 SARI cases per 1000 admitted cases were reported in 2022. The median age among ILI was 12 years (IQR: 5-28) and SARI was 6.2 (IQR: 2.5-15) years. Flu A(H3N2) (70.2%) subtype was the most predominant circulating strain. Flu A(H1N1)pdm09 and Flu B viruses belonged to subclades that were mismatched to the vaccine strains recommended for the 2021-2022 season but matched the vaccine strain for the 2022-2023 season with vaccine efficacy 85.14% and 88.07% respectively. Flu A(H3N2) virus belonged to two subclades which differed from the vaccine strains recommended in both the 2021-2022 and 2022-2023 seasons with vaccine efficacy 68.28%. CONCLUSION Flu virus positivity rates were substantially elevated during the Flu season in 2022 compared to 2021. Flu A(H3N2) subtype was the most predominant circulating strain in the country and globally. Genetic characterization of the Flu viruses in Bhutan showed a close relatedness of high vaccine efficacy with the vaccine strain that WHO recommended for the 2022-23 season.
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Affiliation(s)
- Kunzang Dorji
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Chonticha Klungthong
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Tshering Dorji
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Tandin Wangchuk
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Pema Yuden
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Tshering Pelki
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Tara Devi Ghishing
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Govinda Gyemiry
- ICT, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Sonam Gyeltshen
- National Influenza Centre, Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | | | - Wudtichai Manasatienkij
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Sonam Wangchuk
- Royal Centre for Disease Control, Ministry of Health, Thimphu, Bhutan
| | - Aaron Farmer
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
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Din GU, Hasham K, Amjad MN, Hu Y. Natural History of Influenza B Virus-Current Knowledge on Treatment, Resistance and Therapeutic Options. Curr Issues Mol Biol 2023; 46:183-199. [PMID: 38248316 PMCID: PMC10814056 DOI: 10.3390/cimb46010014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 01/23/2024] Open
Abstract
Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987-1988 Yamagata lineage outbreak and the 2001-2002 Victoria lineage outbreak, had a significant global impact. IBV's fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations. This review aims to elucidate IBV's evolutionary genomic organization and life cycle and provide an overview of anti-IBV drugs, resistance, treatment options, and prospects for IBV biology, emphasizing challenges in preventing and treating IBV infection.
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Affiliation(s)
- Ghayyas Ud Din
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
| | - Kinza Hasham
- Sundas Molecular Analysis Center, Sundas Foundation Gujranwala Punjab Pakistan, Gujranwala 50250, Pakistan
| | - Muhammad Nabeel Amjad
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
| | - Yihong Hu
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
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Zhang H, Ren X, Tian K, Yu J, Zhu A, Zhang L, Gao GF, Li Z. The Impact and Vaccination Coverage of Seasonal Influenza among Children Aged 6-59 Months in China in 2017-2018: An Internet Panel Survey. Vaccines (Basel) 2022; 10:vaccines10040630. [PMID: 35455379 PMCID: PMC9031834 DOI: 10.3390/vaccines10040630] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/02/2022] [Accepted: 04/12/2022] [Indexed: 02/05/2023] Open
Abstract
Seasonal influenza vaccination is highly recommended for 6-59-month-old children. To determine the impact of seasonal influenza and the factors affecting influenza vaccine uptake among children, we conducted an opt-in Internet panel survey of parents from 21 March 2018 to 1 April 2018. Overall, 40.5% (1913/4719) of children experienced influenza-like illness (ILI), 92.4% of parents sought medical care for children with ILI (outpatients: 61.2%, inpatients: 12.8%), 39.6% of parents preferred to take their sick child to a tertiary hospital, and 57.3% of family members requested leave to care for children with ILI. There was a median of three days of absenteeism (2, 5) per sick child, and 39.4% of children received the influenza vaccine during the 2017-2018 influenza season. Vaccine coverage among children aged 6-11 months and 48-59 months was lower than that among 12-47-month-old children. The top three reasons for not vaccinating were: the influenza vaccine was not recommended by healthcare workers (21.1%), no knowledge about the influenza vaccine (19.2%), and lack of confidence in the vaccine's effectiveness (14.3%). Our findings highlight the need for awareness about the severity of influenza, hygiene behavior, and effectiveness of the influenza vaccine among children and their family members in China.
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Affiliation(s)
- Hangjie Zhang
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100101, China;
- The Center for Disease Control and Prevention of Zhejiang Province, Hangzhou 310051, China
- Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (K.T.); (L.Z.)
| | - Xiang Ren
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (X.R.); (J.Y.); (A.Z.)
| | - Keqing Tian
- Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (K.T.); (L.Z.)
| | - Jianxing Yu
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (X.R.); (J.Y.); (A.Z.)
| | - Aiqing Zhu
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (X.R.); (J.Y.); (A.Z.)
| | - Lijie Zhang
- Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (K.T.); (L.Z.)
| | - George Fu Gao
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100101, China;
- Correspondence: (G.F.G.); (Z.L.); Tel.: +86-10-5890-0211 (G.F.G.); +86-10-5890-0547 (Z.L.)
| | - Zhongjie Li
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 100101, China; (X.R.); (J.Y.); (A.Z.)
- Correspondence: (G.F.G.); (Z.L.); Tel.: +86-10-5890-0211 (G.F.G.); +86-10-5890-0547 (Z.L.)
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Vinh DN, Nhat NTD, de Bruin E, Vy NHT, Thao TTN, Phuong HT, Anh PH, Todd S, Quan TM, Thanh NTL, Lien NTN, Ha NTH, Hong TTK, Thai PQ, Choisy M, Nguyen TD, Simmons CP, Thwaites GE, Clapham HE, Chau NVV, Koopmans M, Boni MF. Age-seroprevalence curves for the multi-strain structure of influenza A virus. Nat Commun 2021; 12:6680. [PMID: 34795239 PMCID: PMC8602397 DOI: 10.1038/s41467-021-26948-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/27/2021] [Indexed: 11/21/2022] Open
Abstract
The relationship between age and seroprevalence can be used to estimate the annual attack rate of an infectious disease. For pathogens with multiple serologically distinct strains, there is a need to describe composite exposure to an antigenically variable group of pathogens. In this study, we assay 24,402 general-population serum samples, collected in Vietnam between 2009 to 2015, for antibodies to eleven human influenza A strains. We report that a principal components decomposition of antibody titer data gives the first principal component as an appropriate surrogate for seroprevalence; this results in annual attack rate estimates of 25.6% (95% CI: 24.1% - 27.1%) for subtype H3 and 16.0% (95% CI: 14.7% - 17.3%) for subtype H1. The remaining principal components separate the strains by serological similarity and associate birth cohorts with their particular influenza histories. Our work shows that dimensionality reduction can be used on human antibody profiles to construct an age-seroprevalence relationship for antigenically variable pathogens.
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MESH Headings
- Algorithms
- Antibodies, Viral/blood
- Antibodies, Viral/immunology
- Geography
- Hemagglutinin Glycoproteins, Influenza Virus/immunology
- Humans
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Influenza A Virus, H1N1 Subtype/immunology
- Influenza A Virus, H1N1 Subtype/physiology
- Influenza A Virus, H3N2 Subtype/immunology
- Influenza A Virus, H3N2 Subtype/physiology
- Influenza A virus/classification
- Influenza A virus/immunology
- Influenza A virus/physiology
- Influenza, Human/epidemiology
- Influenza, Human/immunology
- Influenza, Human/virology
- Models, Theoretical
- Seroepidemiologic Studies
- Time Factors
- Vietnam/epidemiology
- Virus Replication/immunology
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Affiliation(s)
- Dao Nguyen Vinh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nguyen Thi Duy Nhat
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - Erwin de Bruin
- Department of Viroscience, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Nguyen Ha Thao Vy
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Tran Thi Nhu Thao
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Huynh Thi Phuong
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Pham Hong Anh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Stacy Todd
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Liverpool School of Tropical Medicine, Liverpool, UK
- Tropical and Infectious Disease Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, England
| | - Tran Minh Quan
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nguyen Thi Le Thanh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | | | | | | | - Pham Quang Thai
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Marc Choisy
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Tran Dang Nguyen
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - Cameron P Simmons
- Institute of Vector Borne Disease, Monash University, Melbourne, VIC, Australia
| | - Guy E Thwaites
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Hannah E Clapham
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | | | - Marion Koopmans
- Department of Viroscience, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Maciej F Boni
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA, USA.
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Capacity and use of diagnostics and treatment for patients with severe acute respiratory infections in the pre-COVID-19 era in district and provincial hospitals in Viet Nam. Western Pac Surveill Response J 2021; 12:1-9. [PMID: 35251746 PMCID: PMC8873919 DOI: 10.5365/wpsar.2021.12.4.835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Objective To describe the burden of severe acute respiratory infection (SARI) and the infrastructure and current practices of SARI management in hospitals in Viet Nam. Methods We conducted a short observational study at critical care units (CCUs) in 32 district hospitals and 16 provincial hospitals in five provinces in Viet Nam from March to July 2019. We collected data on hospital equipment and medicines used in SARI management. At the patient level, data were collected for 14 consecutive days on all patients presenting to CCUs, including information on demographics, intervention and treatment within 24 hours of CCU admission and 7-day outcome. Results There were significant differences between district and provincial hospitals in the availability of microbial culture, rapid influenza diagnostic tests, inflammatory markers and mechanical ventilation. Among 1722 eligible patients admitted to CCUs, there were 395 (22.9%) patients with SARI. The median age of SARI patients was 74 (interquartile range: 58–84) years; 49.1% were male. Although systemic antibiotics were available in all hospitals and were empirically given to 93.4% of patients, oseltamivir was available in 25% of hospitals, and only 0.5% of patients received empiric oseltamivir within 24 hours of admission. The 7-day mortality was 6.6% (26/395). Independent factors associated with 7-day mortality were septic shock and requiring respiratory support within 24 hours of admission. Discussion SARI is a major burden on CCUs in Viet Nam. Barriers to delivering quality care include the limited availability of diagnostics and medication and non-protocolized management of SARI in CCUs.
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Khanh NC, Fowlkes AL, Nghia ND, Duong TN, Tu NH, Tu TA, McFarland JW, Nguyen TTM, Ha NT, Gould PL, Thanh PN, Trang NTH, Mai VQ, Thi PN, Otsu S, Azziz-Baumgartner E, Anh DD, Iuliano AD. Burden of Influenza-Associated Respiratory Hospitalizations, Vietnam, 2014-2016. Emerg Infect Dis 2021; 27:2648-2657. [PMID: 34545793 PMCID: PMC8462305 DOI: 10.3201/eid2710.204765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Influenza burden estimates are essential to informing prevention and control policies. To complement recent influenza vaccine production capacity in Vietnam, we used acute respiratory infection (ARI) hospitalization data, severe acute respiratory infection (SARI) surveillance data, and provincial population data from 4 provinces representing Vietnam’s major regions during 2014–2016 to calculate provincial and national influenza-associated ARI and SARI hospitalization rates. We determined the proportion of ARI admissions meeting the World Health Organization SARI case definition through medical record review. The mean influenza-associated hospitalization rates per 100,000 population were 218 (95% uncertainty interval [UI] 197–238) for ARI and 134 (95% UI 119–149) for SARI. Influenza-associated SARI hospitalization rates per 100,000 population were highest among children <5 years of age (1,123; 95% UI 946–1,301) and adults >65 years of age (207; 95% UI 186–227), underscoring the need for prevention and control measures, such as vaccination, in these at-risk populations.
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Thiem VD, Chabanon AL, Fournier M, Lavis N, Quang ND, Ha VH, Sanicas M. Safety of a quadrivalent influenza vaccine in Vietnamese healthy subjects aged 6 months and older. Hum Vaccin Immunother 2021; 17:690-693. [PMID: 32783746 PMCID: PMC7993207 DOI: 10.1080/21645515.2020.1795477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Quadrivalent influenza vaccines (QIVs) provide protection against the two influenza A viruses (H1N1 and H3N2) and both co-circulating influenza B lineages. QIVs have been found safe, immunogenic, and efficacious in several phase III clinical trials. Here we assess the safety of QIV after vaccination in Vietnamese infants, children, and adults. Participants (n = 228) were asked to report any solicited adverse events (AEs) occurring within 7 days, unsolicited non-serious AEs occurring within 28 days post-vaccination, and serious adverse events (SAEs) at any time during the study. The study was completed by 224 participants (97.4%). Thirty-one children (39.7%) aged 6 − 35 months, 32 children (40.0%) aged 3 − 8 years, 2 participants (9.0%) aged 9 − 17 years, 5 participants (17.9%) aged 18 − 60 years, and 3 participants (15.0%) aged ≥60 years reported ≥1 solicited reaction within 7 days following vaccination. The most frequent-solicited AEs were injection-site tenderness or pain, appetite loss, fever, and abnormal crying in 6 − 35 month-olds, and fever, headache, and myalgia in other age groups. No severe-unsolicited AEs or vaccine-related SAEs were reported. These results suggest that QIV is well tolerated across age groups in Vietnam, and can be safely used to protect the Vietnamese population against influenza and its potentially serious complications.
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Affiliation(s)
- Vu Dinh Thiem
- Center for Clinical Trials, National Institute of Hygiene and Epidemiology (NIHE), Hanoi, Vietnam
| | | | - Marion Fournier
- Sanofi Pasteur, Medical Operations, Campus Sanofi Lyon, Lyon, France
| | - Nathalie Lavis
- Sanofi Pasteur, Medical Operations, Campus Sanofi Lyon, Lyon, France
| | - Nguyen Dang Quang
- Center for Clinical Trials, National Institute of Hygiene and Epidemiology (NIHE), Hanoi, Vietnam
| | - Vu Hai Ha
- Center for Clinical Trials, National Institute of Hygiene and Epidemiology (NIHE), Hanoi, Vietnam
| | - Melvin Sanicas
- Sanofi Pasteur Medical Asia and JPAC, Sanofi-Aventis (Singapore) Pte. Ltd, Singapore, Singapore
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Chen L, Han X, Bai L, Zhang J. Clinical characteristics and outcomes in adult patients hospitalized with influenza, respiratory syncytial virus and human metapneumovirus infections. Expert Rev Anti Infect Ther 2020; 19:787-796. [PMID: 33141622 DOI: 10.1080/14787210.2021.1846520] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Objectives: To compare the clinical characteristics and outcomes of patients hospitalized with respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and influenza infections.Methods: This study prospectively enrolled 594 patients hospitalized with influenza-like illness (ILI) and laboratory-confirmed RSV, hMPV, or influenza infections over three consecutive influenza seasons at a tertiary hospital in China.Results: While certain clinical features were of value as predictors of infection type, none exhibited good predictive performance as a means of discriminating between these three infections (area under the receiver-operating characteristic curve < 0.70). After controlling for potential confounding variables, RSV infections in pneumonia patients were found to be associated with a 30-day mortality risk comparable to that of influenza patients [odds ratio (OR) 1.016, 95% confidence interval (CI) 0.267-3.856, p = 0.982], whereas hMPV infection was associated with a reduced risk of mortality (OR 0.144, 95% CI 0.027-0.780, p = 0.025). Among those without pneumonia, the 30-day mortality risk in patients with influenza was comparable to that in patients infected with RSV (OR 1.268, 95% CI 0.172-9.355, p = 0.816) or hMPV (OR 1.128, 95% CI 0.122-10.419, p = 0.916).Conclusion: Disease severity associated with these three types of viral infection was inconsistent when comparing patients with and without pneumonia, highlighting the importance of etiologic testing.
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Affiliation(s)
- Liang Chen
- Department of Infectious Diseases, Beijing Jishuitan Hospital, 4th Medical College of Peking University, Beijing, China
| | - Xiudi Han
- Department of Pulmonary and Critical Care Medicine, Qingdao Municipal Hospital, Qingdao City, Shandong Province, China
| | - Lu Bai
- Department of Infectious Diseases, Beijing Jishuitan Hospital, 4th Medical College of Peking University, Beijing, China
| | - Jian Zhang
- Department of Infectious Diseases, Beijing Jishuitan Hospital, 4th Medical College of Peking University, Beijing, China
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Umuhoza T, Bulimo WD, Oyugi J, Schnabel D, Mancuso JD. Prevalence and factors influencing the distribution of influenza viruses in Kenya: Seven-year hospital-based surveillance of influenza-like illness (2007-2013). PLoS One 2020; 15:e0237857. [PMID: 32822390 PMCID: PMC7446924 DOI: 10.1371/journal.pone.0237857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 08/04/2020] [Indexed: 12/03/2022] Open
Abstract
Background Influenza viruses remain a global threat with the potential to trigger outbreaks and pandemics. Globally, seasonal influenza viruses’ mortality range from 291 243–645 832 annually, of which 17% occurs in Sub-Saharan Africa. We sought to estimate the overall prevalence of influenza infections in Kenya, identifying factors influencing the distribution of these infections, and describe trends in occurrence from 2007 to 2013. Methods Surveillance was conducted at eight district hospital sites countrywide. Participants who met the case definition for influenza-like illness were enrolled in the surveillance program. The nasopharyngeal specimens were collected from all participants. We tested all specimens for influenza viruses with quantitative reverse transcriptase real-time polymerase chain reaction (RT-qPCR) assay. Bivariate and multivariate log-binomial regression was performed with a statistically significant level of p<0.005. An administrative map of Kenya was used to locate the geographical distribution of surveillance sites in counties. We visualized the monthly trend of influenza viruses with a graph and chart using exponential smoothing at a damping factor of 0.5 over the study period (2007–2013). Results A total of 17446 participants enrolled in the program. The overall prevalence of influenza viruses was 19% (n = 3230), of which 76% (n = 2449) were type A, 21% (n = 669) type B and 3% (n = 112) A/ B coinfection. Of those with type A, 59% (n = 1451) were not subtyped. Seasonal influenza A/H3N2 was found in 48% (n = 475), influenza A/H1N1/pdm 2009 in 43% (n = 434), and seasonal influenza A/ H1N1 in 9% (n = 88) participants. Both genders were represented, whereas a large proportion of participants 55% were ≤1year age. Influenza prevalence was high, 2 times more in other age categories compared to ≤1year age. Category of occupation other than children and school attendees had a high prevalence of influenza virus (p< <0.001). The monthly trends of influenza viruses’ positivity showed no seasonal pattern. Influenza types A and B co-circulated throughout the annual calendar during seven years of the surveillance. Conclusions Influenza viruses circulate year-round and occur among children as well as the adult population in Kenya. Occupational and school-based settings showed a higher prevalence of influenza viruses. There were no regular seasonal patterns for influenza viruses.
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Affiliation(s)
- Therese Umuhoza
- Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya
| | - Wallace D. Bulimo
- Department of Emerging Infectious Diseases, United State Army Medical Research Directorate – Africa, Nairobi, Kenya
- Department of Biochemistry, School of Medicine, University of Nairobi, Nairobi, Kenya
- * E-mail:
| | - Julius Oyugi
- Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya
| | - David Schnabel
- US President’s Malaria Initiative, Freetown, Sierra Leone
| | - James D. Mancuso
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
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Zhu A, Liu J, Ye C, Yu J, Peng Z, Feng L, Wang L, Qin Y, Zheng Y, Li Z. Characteristics of Seasonal Influenza Virus Activity in a Subtropical City in China, 2013-2019. Vaccines (Basel) 2020; 8:vaccines8010108. [PMID: 32121519 PMCID: PMC7157579 DOI: 10.3390/vaccines8010108] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 02/27/2020] [Accepted: 02/27/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND To optimize seasonal influenza vaccination programs in regions with potentially complicated seasonal patterns, the epidemiological characteristics of seasonal influenza activity in a subtropical city of China were explored. MATERIALS AND METHODS Influenza virus data of patients with influenza-like illness (ILI) during 2013-2019 were collected from two sentinel hospitals in a subtropical region of China, Yichang city. The influenza virus positive rate among sampled ILI cases served as a proxy to estimate influenza seasonal characteristics, including periodicity, duration, peaks, and predominant subtypes/lineages. Epidemiological features of different years, seasons and age groups were analyzed, and vaccine mismatches were identified. RESULTS In total, 8693 ILI cases were included; 1439 (16.6%) were laboratory-confirmed influenza cases. The influenza A positive rate (10.6%) was higher than the influenza B positive rate (5.9%). There were three influenza circulation patterns in Yichang: (1) annual periodicity (in 2013-2014, 2015-2016 and 2018-2019), (2) semiannual periodicity (in 2014-2015), and (3) year-round periodicity (in 2016-2017 and 2017-2018). Summer epidemics existed in two of the six years and were dominated by influenza A/H3N2. Winter and spring epidemics occurred in five of the six years, and A/H1N1, A/H3N2, B/Victoria, and B/Yamagata were codominant. During the study period, the predominant lineages, B/Victoria in 2015-16 and B/Yamagata in 2017-2018, were both mismatched with the influenza B component of the trivalent vaccine. Children 5-14 years old (26.4%) and individuals over 60 years old (16.9%) had the highest influenza positive rates. CONCLUSIONS The seasonal epidemic period and the predominant subtype/lineage of influenza viruses in Yichang city are complex. Influenza vaccination timing and strategies need to be optimized according to the local features of influenza virus activity.
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Affiliation(s)
- Aiqin Zhu
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Jianhua Liu
- Yichang Center for Disease Control and Prevention, Yichang 443003, China;
| | - Chuchu Ye
- Research Base of Key Laboratory of Surveillance and Early Warning of Infectious Disease, Pudong New Area Center for Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Shanghai 200136, China;
| | - Jianxing Yu
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Zhibing Peng
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Luzhao Feng
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Liping Wang
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Ying Qin
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Yaming Zheng
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
| | - Zhongjie Li
- Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; (A.Z.); (J.Y.); (Z.P.); (L.F.); (L.W.); (Y.Q.); (Y.Z.)
- Correspondence: ; Tel.: +86-010-5890-0543
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11
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Epidemiological features and time-series analysis of influenza incidence in urban and rural areas of Shenyang, China, 2010-2018. Epidemiol Infect 2020; 148:e29. [PMID: 32054544 PMCID: PMC7026897 DOI: 10.1017/s0950268820000151] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In recent years, there have been a significant influenza activity and emerging influenza strains in China, resulting in an increasing number of influenza virus infections and leading to public health concerns. The aims of this study were to identify the epidemiological and aetiological characteristics of influenza and establish seasonal autoregressive integrated moving average (SARIMA) models for forecasting the percentage of visits for influenza-like illness (ILI%) in urban and rural areas of Shenyang. Influenza surveillance data were obtained for ILI cases and influenza virus positivity from 18 sentinel hospitals. The SARIMA models were constructed to predict ILI% for January–December 2019. During 2010–2018, the influenza activity was higher in urban than in rural areas. The age distribution of ILI cases showed the highest rate in young children aged 0–4 years. Seasonal A/H3N2, influenza B virus and pandemic A/H1N1 continuously co-circulated in winter and spring seasons. In addition, the SARIMA (0, 1, 0) (0, 1, 2)12 model for the urban area and the SARIMA (1, 1, 1) (1, 1, 0)12 model for the rural area were appropriate for predicting influenza incidence. Our findings suggested that there were regional and seasonal distinctions of ILI activity in Shenyang. A co-epidemic pattern of influenza strains was evident in terms of seasonal influenza activity. Young children were more susceptible to influenza virus infection than adults. These results provide a reference for future influenza prevention and control strategies in the study area.
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12
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Tuyet Hanh TT, Huong LTT, Huong NTL, Linh TNQ, Quyen NH, Nhung NTT, Ebi K, Cuong ND, Van Nhu H, Kien TM, Hales S, Cuong DM, Tho NTT, Toan LQ, Bich NN, Van Minh H. Vietnam Climate Change and Health Vulnerability and Adaptation Assessment, 2018. ENVIRONMENTAL HEALTH INSIGHTS 2020; 14:1178630220924658. [PMID: 32612364 PMCID: PMC7309337 DOI: 10.1177/1178630220924658] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND The Global Climate Risk Index 2020 ranked Vietnam as the sixth country in the world most affected by climate variability and extreme weather events over the period 1999-2018. Sea level rise and extreme weather events are projected to be more severe in coming decades, which, without additional action, will increase the number of people at risk of climate-sensitive diseases, challenging the health system. This article summaries the results of a health vulnerability and adaptation (V&A) assessment conducted in Vietnam as evidences for development of the National Climate Change Health Adaptation Plan to 2030. METHODS The assessment followed the first 4 steps outlined in the World Health Organization's Guidelines in conducting "Vulnerability and Adaptation Assessments." A framework and list of indicators were developed for semi-quantitative assessment for the period 2013 to 2017. Three sets of indicators were selected to assess the level of (1) exposure to climate change and extreme weather events, (2) health sensitivity, and (3) adaptation capacity. The indicators were rated and analyzed using a scoring system from 1 to 5. RESULTS The results showed that climate-sensitive diseases were common, including dengue fever, diarrheal, influenza, etc, with large burdens of disease that are projected to increase. From 2013 to 2017, the level of "exposure" to climate change-related hazards of the health sector was "high" to "very high," with an average score from 3.5 to 4.4 (out of 5.0). For "health sensitivity," the scores decreased from 3.8 in 2013 to 3.5 in 2017, making the overall rating as "high." For "adaptive capacity," the scores were from 4.0 to 4.1, which meant adaptive capacity was "very low." The overall V&A rating in 2013 was "very high risk" (score 4.1) and "high risk" with scores of 3.8 in 2014 and 3.7 in 2015 to 2017. CONCLUSIONS Adaptation actions of the health sector are urgently needed to reduce the vulnerability to climate change in coming decades. Eight adaptation solutions, among recommendations of V&A assessment, were adopted in the National Health Climate Change Adaptation Plan.
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Affiliation(s)
- Tran Thi Tuyet Hanh
- Faculty of Environmental and Occupational Health, Hanoi University of Public Health, Hanoi, Vietnam
| | - Le Thi Thanh Huong
- Faculty of Environmental and Occupational Health, Hanoi University of Public Health, Hanoi, Vietnam
- Le Thi Thanh Huong, Hanoi University of Public Health, 1A Duc Thang Road, Duc Thang Ward, North Tu Liem District, Hanoi 100000, Vietnam.
| | | | - Tran Nu Quy Linh
- Center for Environment and Population Health, School of Medicine, Griffith University, Brisbane, Queensland, Australia
| | - Nguyen Huu Quyen
- Climate research and Climate Forecasting Division, Institute of Hydrology and Meteorology Science and Climate Change, Hanoi, Vietnam
| | | | - Kristie Ebi
- Center for Health and the Global Environment, University of Washington, Seattle, WA, USA
| | | | - Ha Van Nhu
- Faculty of Environmental and Occupational Health, Hanoi University of Public Health, Hanoi, Vietnam
| | - Tran Mai Kien
- Climate Change Research Center, Institute of Hydrology and Meteorology Science and Climate Change, Hanoi, Vietnam
| | - Simon Hales
- Public Health Department, University of Otago, Otago, New Zealand
| | - Do Manh Cuong
- Vietnam Health Environment Management Agency, Hanoi, Vietnam
| | - Nguyen Thi Thi Tho
- Department of Non-Communicable Diseases Prevention and Control, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Luu Quoc Toan
- Faculty of Environmental and Occupational Health, Hanoi University of Public Health, Hanoi, Vietnam
| | - Nguyen Ngoc Bich
- Faculty of Environmental and Occupational Health, Hanoi University of Public Health, Hanoi, Vietnam
| | - Hoang Van Minh
- Vice-Rector, Hanoi University of Public Health, Hanoi, Vietnam
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13
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Horwood PF, Karlsson EA, Horm SV, Ly S, Heng S, Chin S, Darapheak C, Saunders D, Chanthap L, Rith S, Y P, Chea KL, Sar B, Parry A, Ieng V, Tsuyouka R, Deng YM, Hurt AC, Barr IG, Komadina N, Buchy P, Dussart P. Circulation and characterization of seasonal influenza viruses in Cambodia, 2012-2015. Influenza Other Respir Viruses 2019; 13:465-476. [PMID: 31251478 PMCID: PMC6692578 DOI: 10.1111/irv.12647] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 12/13/2018] [Accepted: 04/26/2019] [Indexed: 12/04/2022] Open
Abstract
Background Influenza virus circulation is monitored through the Cambodian influenza‐like illness (ILI) sentinel surveillance system and isolates are characterized by the National Influenza Centre (NIC). Seasonal influenza circulation has previously been characterized by year‐round activity and a peak during the rainy season (June‐November). Objectives We documented the circulation of seasonal influenza in Cambodia for 2012‐2015 and investigated genetic, antigenic, and antiviral resistance characteristics of influenza isolates. Patients/Methods Respiratory samples were collected from patients presenting with influenza‐like illness (ILI) at 11 hospitals throughout Cambodia. First‐line screening was conducted by the National Institute of Public Health and the Armed Forces Research Institute of Medical Sciences. Confirmation of testing and genetic, antigenic and antiviral resistance characterization was conducted by Institute Pasteur in Cambodia, the NIC. Additional virus characterization was conducted by the WHO Collaborating Centre for Reference and Research on Influenza (Melbourne, Australia). Results Between 2012 and 2015, 1,238 influenza‐positive samples were submitted to the NIC. Influenza A(H3N2) (55.3%) was the dominant subtype, followed by influenza B (30.9%; predominantly B/Yamagata‐lineage) and A(H1N1)pdm09 (13.9%). Circulation of influenza viruses began earlier in 2014 and 2015 than previously described, coincident with the emergence of A(H3N2) clades 3C.2a and 3C.3a, respectively. There was high diversity in the antigenicity of A(H3N2) viruses, and to a smaller extent influenza B viruses, during this period, with some mismatches with the northern and southern hemisphere vaccine formulations. All isolates tested were susceptible to the influenza antiviral drugs oseltamivir and zanamivir. Conclusions Seasonal and year‐round co‐circulation of multiple influenza types/subtypes were detected in Cambodia during 2012‐2015.
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Affiliation(s)
- Paul F Horwood
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia.,Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Erik A Karlsson
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
| | - Srey Viseth Horm
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
| | - Sovann Ly
- Communicable Disease Control Department, Ministry of Health, Phnom Penh, Cambodia
| | - Seng Heng
- Communicable Disease Control Department, Ministry of Health, Phnom Penh, Cambodia
| | - Savuth Chin
- National Institute of Public Health, Phnom Penh, Cambodia
| | - Chau Darapheak
- National Institute of Public Health, Phnom Penh, Cambodia
| | - David Saunders
- Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Lon Chanthap
- Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Sareth Rith
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
| | - Phalla Y
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
| | - Kim Lay Chea
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
| | - Borann Sar
- Centers for Disease Control and Prevention, Phnom Penh, Cambodia
| | - Amy Parry
- World Health Organization, Phnom Penh, Cambodia
| | - Vanra Ieng
- World Health Organization, Phnom Penh, Cambodia
| | | | - Yi-Mo Deng
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Peter Doherty Institute, Melbourne, Victoria, Australia
| | - Aeron C Hurt
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Peter Doherty Institute, Melbourne, Victoria, Australia
| | - Ian G Barr
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Peter Doherty Institute, Melbourne, Victoria, Australia
| | - Naomi Komadina
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Peter Doherty Institute, Melbourne, Victoria, Australia.,Monash University, Melbourne, Victoria, Australia
| | - Philippe Buchy
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia.,GlaxoSmithKline Vaccines R&D Intercontinental, Singapore, Singapore
| | - Philippe Dussart
- Virology Unit, Institute Pasteur in Cambodia, Institute Pasteur International Network, Phnom Penh, Cambodia
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14
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Ang LW, Cui L, Mak TM, Ng Y, Leo YS, Lee VJM, Lin RTP. Differential age-specific distribution of influenza virus types and subtypes in tropical Singapore, 2011 to 2017. J Med Virol 2019; 91:1415-1422. [PMID: 30927452 DOI: 10.1002/jmv.25473] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 11/06/2022]
Abstract
Surveillance and reporting of epidemiological features of seasonal influenza mostly are aggregates across all-ages. We investigated age-specific differences in distribution of influenza virus (sub)types in tropical Singapore, using laboratory-confirmed virological data collected under the national influenza surveillance programme from 2011 to 2017. The proportion of influenza-positive specimens from outpatients with influenza-like illness was used as an indicator of influenza activity in the community. The highest influenza positivity for age groups of 5 to 14 years and 15 to 64 years coincided in the same month in 5 out of the 7 years under study. Influenza positivity was lowest in young children <5 years of age compared with older age groups. Influenza A(H3N2) was most prevalent in the community except in 2012 when a predominance of influenza B was observed. The dominant virus (sub)type varied across the years in children <5 years and 5 to 14 years of age. Influenza A(H3N2) was the predominant circulating virus subtype among elderly persons aged ≥65 years during the 7-year period, and among adults aged 15 to 64 years since 2013. Knowledge about the age-specific differences in distribution of influenza virus (sub)types helps to facilitate better understanding of seasonal epidemics and to inform targeted strategies in prevention and control of influenza virus transmission.
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Affiliation(s)
- Li Wei Ang
- National Public Health and Epidemiology Unit, National Centre for Infectious Diseases, Singapore.,Public Health Group, Ministry of Health, Singapore
| | - Lin Cui
- National Public Health Laboratory, National Centre for Infectious Diseases, Singapore
| | - Tze Minn Mak
- National Public Health Laboratory, National Centre for Infectious Diseases, Singapore
| | - Yixiang Ng
- Public Health Group, Ministry of Health, Singapore
| | - Yee Sin Leo
- National Centre for Infectious Diseases, Singapore
| | | | - Raymond Tzer-Pin Lin
- National Public Health Laboratory, National Centre for Infectious Diseases, Singapore
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15
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Missed detections of influenza A(H1)pdm09 by real-time RT-PCR assay due to haemagglutinin sequence mutation, December 2017 to March 2018, northern Viet Nam. Western Pac Surveill Response J 2019; 10:32-38. [PMID: 31110840 PMCID: PMC6507123 DOI: 10.5365/wpsar.2018.9.3.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Introduction There are two methods of reverse transcription polymerase chain reaction (RT–PCR) that have been the common methods to detect influenza infections: conventional and real-time RT–PCR. From December 2017 to March 2018, several missed diagnoses of influenza A(H1)pdm09 using real-time RT–PCR were reported in northern Viet Nam. This study investigated how these missed detections occurred to determine their effect on the surveillance of influenza. Methods The haemagglutinin (HA) segments of A(H1N1)pdm09 from both real-time RT–PCR positive and negative samples were isolated and sequenced. The primer and probe sets in the HA gene were checked for mismatches, and phylogenetic analyses were performed to determine the molecular epidemiology of these viruses. Results There were 86 positive influenza A samples; 32 were A(H1)pdm09 positive by conventional RT–PCR but were negative by real-time RT–PCR. Sequencing was conducted on 23 influenza (H1N1)pdm09 isolates that were recovered from positive samples. Eight of these were negative for A(H1)pdm09 by real-time RT–PCR. There were two different mismatches in the probe target sites of the HA gene sequences of all isolates (n = 23) with additional mismatches only at position 7 (template binding site) identified for all eight negative real-time RT–PCR isolates. The prime target sites had no mismatches. Phylogenetic analysis of the HA gene showed that both the positive and negative real-time RT–PCR isolates were grouped in clade 6B.1; however, the real-time RT–PCR negative viruses were located in a subgroup that referred to substitution I295V. Conclusion Constant monitoring of genetic changes in the circulating influenza A(H1N1)pdm09 viruses is important for maintaining the sensitivity of molecular detection assays.
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16
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Luong LMT, Phung D, Sly PD, Dang TN, Morawska L, Thai PK. Effects of temperature on hospitalisation among pre-school children in Hanoi, Vietnam. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:2603-2612. [PMID: 30474814 DOI: 10.1007/s11356-018-3737-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 11/12/2018] [Indexed: 06/09/2023]
Abstract
This study examined the effect of short-term changes in ambient temperature on hospital admissions among children aged less than 5 years old in Hanoi, Vietnam. Data on daily hospital admissions from January 2010 to June 2014 were collected from two hospitals. Daily meteorological data were obtained for the same period. We applied time series analysis to evaluate the risk of hospitalisation related to hot and cold weather by age and causes. We found that a 1 °C decrease in minimum temperature during the cold weather months was associated with 2.2% increase in hospital admission for respiratory infection among children 3-5 years old. A 1 °C increase in diurnal temperature range (DTR) in cold weather was associated with an increase of 1.9% and 1.7% in hospitalisation for all causes and respiratory infection, respectively, among children < 3 years old and an increase of 1.8% and 3.4% in hospitalisation for all causes and respiratory infection, respectively, among children of 3-5 years old. Negative associations between hot weather and hospital admissions were demonstrated. These findings suggested that low temperature and DTRs in winter are important risk factors for hospital admissions among children aged < 5 years old in Hanoi. Other factors may have modified the effect of high temperature on hospital admissions of children in Hanoi.
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Affiliation(s)
- Ly M T Luong
- Faculty of Medicine, The University of Queensland, Brisbane, Australia
- Children's Health and Environment Program, The University of Queensland, Brisbane, Australia
- Faculty of Environmental Sciences, VNU University of Science, Hanoi, Vietnam
| | - Dung Phung
- Centre for Environment and Population Health, Griffith University, Brisbane, Australia.
| | - Peter D Sly
- Children's Health and Environment Program, The University of Queensland, Brisbane, Australia
| | - Tran Ngoc Dang
- Department of Environmental Health, University of Medicine and Pharmacy, Ho Chi Minh, Vietnam
- The Institute of Research and Development, Duy Tan University, Da Nang City, Vietnam
| | - Lidia Morawska
- International Laboratory for Air Quality & Health, Queensland University of Technology, Brisbane, Australia
| | - Phong K Thai
- International Laboratory for Air Quality & Health, Queensland University of Technology, Brisbane, Australia.
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17
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Le-Viet N, Le VN, Chung H, Phan DT, Phan QD, Cao TV, Abat C, Raoult D, Parola P. Prospective case-control analysis of the aetiologies of acute undifferentiated fever in Vietnam. Emerg Microbes Infect 2019; 8:339-352. [PMID: 30866787 PMCID: PMC6455186 DOI: 10.1080/22221751.2019.1580539] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/24/2019] [Accepted: 01/29/2019] [Indexed: 01/15/2023]
Abstract
Acute undifferentiated fever (AUF) is frequently observed in tropical settings, but diagnosing the cause of AUF is often a challenge for local physicians and the physicians treating returning travellers. We conducted a case-control study in central Vietnam in 2016. A total of 378 febrile adult patients (AUFs) with a fever for ≤21 days, no evidence of localized infection and negative screening tests for dengue and malaria, and 384 afebrile adult patients (Controls) were prospectively enrolled. Whole blood, plasma, eschar swab, throat swab and urine specimens were collected and analysed. Quantitative PCR and RT-PCR were used to test for 55 bacteria, viruses and their subtypes. Serological tests were also used to test for rickettsial agents. The most common aetiology was influenza virus (20.9% in AUFs vs. 0% in Controls), followed by rickettsial agents (mainly Orientia tsutsugamushi and Rickettsia typhi) (10.8% vs. 0.3%), dengue virus (7.7% vs. 0.5%), Leptospira (4.8% vs. 0.8%), adenovirus (4.8% vs. 1.0%), and enterovirus (2.1% vs. 0%) (p < .05). The real proportion of dengue in AUF cases was underestimated because patients with dengue-positive rapid diagnosis tests were excluded from the study. The emerging agent Rickettsia felis, which had not been previously observed in Vietnam, was detected in this study. In total, 216 patients (57.1%) were given causative diagnoses, comprising 143 (66.2%) monoinfections and 73 (33.8%) coinfections. The infections caused by these agents should be considered in clinical practice and further studies. Additionally, agents susceptible to doxycycline were detected in 15.6% of AUFs; thus, this drug should be included in the panel used to treat AUF patients.
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Affiliation(s)
- Nhiem Le-Viet
- Aix Marseille University, IRD, AP-HM, SSA, VITROME, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
- Department of Tropical Medicine, Quang Nam Central General Hospital, Quang Nam, Vietnam
| | - Viet-Nho Le
- School of Medicine and Pharmacy, Danang University, Danang, Vietnam
| | - Hai Chung
- Department of Tropical Medicine, Quang Nam Central General Hospital, Quang Nam, Vietnam
| | - Duc-Tuan Phan
- Department of Internal Medicine II, Quang Nam Northern Mountainous Region General Hospital, Quang Nam, Vietnam
| | - Quang-Duong Phan
- Department of Internal Medicine B, Quang Nam Regional General Hospital, Quang Nam, Vietnam
| | - Thanh-Van Cao
- Department of Tropical Medicine, Quang Nam Provincial General Hospital, Quang Nam, Vietnam
| | - Cédric Abat
- IHU-Méditerranée Infection, Marseille, France
| | - Didier Raoult
- IHU-Méditerranée Infection, Marseille, France
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
| | - Philippe Parola
- Aix Marseille University, IRD, AP-HM, SSA, VITROME, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
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18
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Lam HM, Wesolowski A, Hung NT, Nguyen TD, Nhat NTD, Todd S, Vinh DN, Vy NHT, Thao TTN, Thanh NTL, Tin PT, Minh NNQ, Bryant JE, Buckee CO, Ngoc TV, Chau NVV, Thwaites GE, Farrar J, Tam DTH, Vinh H, Boni MF. Nonannual seasonality of influenza-like illness in a tropical urban setting. Influenza Other Respir Viruses 2018; 12:742-754. [PMID: 30044029 PMCID: PMC6185894 DOI: 10.1111/irv.12595] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In temperate and subtropical climates, respiratory diseases exhibit seasonal peaks in winter. In the tropics, with no winter, peak timings are irregular. METHODS To obtain a detailed picture of influenza-like illness (ILI) patterns in the tropics, we established an mHealth study in community clinics in Ho Chi Minh City (HCMC). During 2009-2015, clinics reported daily case numbers via SMS, with a subset performing molecular diagnostics for influenza virus. This real-time epidemiology network absorbs 6000 ILI reports annually, one or two orders of magnitude more than typical surveillance systems. A real-time online ILI indicator was developed to inform clinicians of the daily ILI activity in HCMC. RESULTS From August 2009 to December 2015, 63 clinics were enrolled and 36 920 SMS reports were received, covering approximately 1.7M outpatient visits. Approximately 10.6% of outpatients met the ILI case definition. ILI activity in HCMC exhibited strong nonannual dynamics with a dominant periodicity of 206 days. This was confirmed by time series decomposition, stepwise regression, and a forecasting exercise showing that median forecasting errors are 30%-40% lower when using a 206-day cycle. In ILI patients from whom nasopharyngeal swabs were taken, 31.2% were positive for influenza. There was no correlation between the ILI time series and the time series of influenza, influenza A, or influenza B (all P > 0.15). CONCLUSION This suggests, for the first time, that a nonannual cycle may be an essential driver of respiratory disease dynamics in the tropics. An immunological interference hypothesis is discussed as a potential underlying mechanism.
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Affiliation(s)
- Ha Minh Lam
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Amy Wesolowski
- Center for Communicable Disease DynamicsDepartment of EpidemiologyHarvard T.H. Chan School of Public HealthBostonMassachusetts
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
| | - Nguyen Thanh Hung
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Tran Dang Nguyen
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Thi Duy Nhat
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Stacy Todd
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Liverpool School of Tropical MedicineLiverpoolUK
| | - Dao Nguyen Vinh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Ha Thao Vy
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Tran Thi Nhu Thao
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Thi Le Thanh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | | | - Ngo Ngoc Quang Minh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Children's Hospital No. 1Ho Chi Minh CityVietnam
| | - Juliet E. Bryant
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Caroline O. Buckee
- Center for Communicable Disease DynamicsDepartment of EpidemiologyHarvard T.H. Chan School of Public HealthBostonMassachusetts
| | - Tran Van Ngoc
- Hospital for Tropical DiseasesHo Chi Minh CityVietnam
| | | | - Guy E. Thwaites
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Jeremy Farrar
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Wellcome TrustLondonUK
| | - Dong Thi Hoai Tam
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Ha Vinh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Hospital for Tropical DiseasesHo Chi Minh CityVietnam
- Department of Infectious DiseasesPham Ngoc Thach University of MedicineHo Chi Minh CityVietnam
| | - Maciej F. Boni
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
- Center for Infectious Disease DynamicsDepartment of BiologyPennsylvania State UniversityUniversity ParkPennsylvania
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19
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Todd S, Huong NTC, Thanh NTL, Vy NHT, Hung NT, Thao TTN, Phuong HT, van Doorn R, Hang VTT, Chau NVV, Read JM, Lalloo DG, Boni MF. Primary care influenza-like illness surveillance in Ho Chi Minh City, Vietnam 2013-2015. Influenza Other Respir Viruses 2018; 12:623-631. [PMID: 29858879 PMCID: PMC6086852 DOI: 10.1111/irv.12574] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2018] [Indexed: 12/22/2022] Open
Abstract
Background Year‐round transmission of influenza has been detected in Vietnam through both national surveillance and other epidemiological studies. Understanding the demographic and clinical features of influenza‐like illness (ILI) presenting to primary care in urban Vietnam is vital to understand these transmission dynamics. Methods An observational study of patients with ILI in Ho Chi Minh City, Vietnam, was conducted between August 2013 and November 2015 in a mix of public and private primary care settings. Molecular testing for influenza A and influenza B and 12 other respiratory viruses was performed. Results A total of 1152 ILI patients were recruited. 322 and 136 subjects tested positive for influenza A and influenza B, respectively. 193 subjects tested positive for another respiratory virus; most commonly rhinovirus and parainfluenza virus 3. Influenza was detected in 81% of the 116 study weeks. Three peaks of influenza activity were detected; an H3N2 peak April‐June 2014, an influenza B peak July‐December 2014, and a mixed H3N2 and H1N1 peak March‐September 2015. Subjects recruited from private clinics were more likely to have higher income and to have reported previous influenza vaccination. Antibiotic use was common (50.3%) despite limited evidence of bacterial infection. Conclusion Influenza in southern Vietnam has complex transmission dynamics including periods of intense influenza activity of alternating types and subtypes. Broadening surveillance from hospital to the community in tropical settings is feasible and a valuable for improving our understanding of the global spread and evolution of the virus.
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Affiliation(s)
- Stacy Todd
- Liverpool School of Tropical Medicine, Liverpool, UK.,Tropical and Infectious Disease Unit, Royal Liverpool and Broadgreen University Hospital, Liverpool, UK.,Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | | | - Nguyen Thi Le Thanh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nguyen Ha Thao Vy
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nguyen Thanh Hung
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Tran Thi Nhu Thao
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Huynh Thi Phuong
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Rogier van Doorn
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Vu Thi Ty Hang
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nguyen Van Vinh Chau
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Jonathan M Read
- Centre for Health Informatics Computing and Statistics, Lancaster Medical School, Lancaster University, Lancaster, UK.,Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - David G Lalloo
- Liverpool School of Tropical Medicine, Liverpool, UK.,Tropical and Infectious Disease Unit, Royal Liverpool and Broadgreen University Hospital, Liverpool, UK
| | - Maciej F Boni
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.,Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA, USA
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20
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Baudon E, Chu DKW, Tung DD, Thi Nga P, Vu Mai Phuong H, Le Khanh Hang N, Thanh LT, Thuy NT, Khanh NC, Mai LQ, Khong NV, Cowling BJ, Peyre M, Peiris M. Swine influenza viruses in Northern Vietnam in 2013-2014. Emerg Microbes Infect 2018; 7:123. [PMID: 29967457 PMCID: PMC6028489 DOI: 10.1038/s41426-018-0109-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/13/2018] [Accepted: 05/16/2018] [Indexed: 12/31/2022]
Abstract
Swine are an important intermediate host for emergence of pandemic influenza. Vietnam is the largest swine producer in South East Asia. Systematic virological and serological surveillance of swine influenza viruses was carried out in Northern Vietnam from May 2013 to June 2014 with monthly sampling of pigs in local and large collective slaughterhouses and in a live pig market. Influenza A seroprevalence in the local slaughterhouses and in the large collective slaughterhouse was 48.7% and 29.1%, respectively. Seventy-seven influenza A viruses were isolated, all from the large collective slaughterhouse. Genetic analysis revealed six virus genotypes including H1N1 2009 pandemic (H1N1pdm09) viruses, H1N2 with H1 of human origin, H3N2 and H1N1pdm09 reassortants, and triple-reassortant H3N2 viruses. Phylogenetic analysis of swine and human H1N1pdm09 viruses showed evidence of repeated spill-over from humans to swine rather than the establishment of H1N1pdm09 as long-term distinct lineage in swine. Surveillance at the large collective slaughterhouse proved to be the most efficient, cost-effective, and sustainable method of surveillance for swine influenza viruses in Vietnam.
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Affiliation(s)
- Eugénie Baudon
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong-Hong Kong Special Administrative Region, Hong Kong, China
- Animal and Integrated Risk Management Research Unit (AGIRs), French Agricultural Research Center for International Development (CIRAD), Montpellier, France
| | - Daniel K W Chu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong-Hong Kong Special Administrative Region, Hong Kong, China
| | - Dao Duy Tung
- National Institute of Veterinary Research, Hanoi, Vietnam
| | - Pham Thi Nga
- National Institute of Veterinary Research, Hanoi, Vietnam
| | | | | | - Le Thi Thanh
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | | | | | - Lê Quynh Mai
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | | | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong-Hong Kong Special Administrative Region, Hong Kong, China
| | - Marisa Peyre
- Animal and Integrated Risk Management Research Unit (AGIRs), French Agricultural Research Center for International Development (CIRAD), Montpellier, France
| | - Malik Peiris
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong-Hong Kong Special Administrative Region, Hong Kong, China.
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21
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Panatto D, Signori A, Lai PL, Gasparini R, Amicizia D. Heterogeneous estimates of influenza virus types A and B in the elderly: Results of a meta-regression analysis. Influenza Other Respir Viruses 2018; 12:533-543. [PMID: 29498477 PMCID: PMC6005586 DOI: 10.1111/irv.12550] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2018] [Indexed: 02/06/2023] Open
Abstract
Influenza has many age‐dependent characteristics. A previous systematic review of randomized controlled trials showed that the detection rate of influenza B was higher in children than in non‐elderly adults. However, no comprehensive reviews have targeted the elderly, who carry the main burden of disease. We aimed to quantify the relative detection rates of virus types A and B among the elderly, to identify factors affecting these proportions, and to compare type distribution among seniors and younger age‐classes. A comprehensive literature search was conducted to identify multiseason studies reporting A and B virus type distributions in the elderly. A random‐effects meta‐analysis was planned to quantify the prevalence of type B among elderly subjects with laboratory‐confirmed influenza. Meta‐regression was then applied to explain the sources of heterogeneity. Across 27 estimates identified, the type B detection rate among seniors varied from 5% to 37%. Meta‐analysis was not feasible owing to high heterogeneity (I2 = 98.5%). Meta‐regression analysis showed that study characteristics, such as number of seasons included, hemisphere, and setting, could have contributed to the heterogeneity observed. The final adjusted model showed that studies that included both outpatients and inpatients reported a significantly (P = .024) lower proportion than those involving outpatients only. The detection rate of type B among the elderly was generally lower than in children/adolescents, but not non‐elderly adults. Influenza virus type B has a relatively low detection rate in older adults, especially in settings covering both inpatients and outpatients. Public health implications are discussed.
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Affiliation(s)
- Donatella Panatto
- Department of Health Sciences, University of Genoa, Genoa, Italy.,Interuniversity Research Center on Influenza and other Transmissible Infections (CIRI-IT), Genoa, Italy
| | - Alessio Signori
- Department of Health Sciences, University of Genoa, Genoa, Italy
| | - Piero L Lai
- Department of Health Sciences, University of Genoa, Genoa, Italy.,Interuniversity Research Center on Influenza and other Transmissible Infections (CIRI-IT), Genoa, Italy
| | - Roberto Gasparini
- Department of Health Sciences, University of Genoa, Genoa, Italy.,Interuniversity Research Center on Influenza and other Transmissible Infections (CIRI-IT), Genoa, Italy
| | - Daniela Amicizia
- Department of Health Sciences, University of Genoa, Genoa, Italy.,Interuniversity Research Center on Influenza and other Transmissible Infections (CIRI-IT), Genoa, Italy
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22
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Jennings L, Huang QS, Barr I, Lee PI, Kim WJ, Buchy P, Sanicas M, Mungall BA, Chen J. Literature review of the epidemiology of influenza B disease in 15 countries in the Asia-Pacific region. Influenza Other Respir Viruses 2018; 12:383-411. [PMID: 29127742 PMCID: PMC5907823 DOI: 10.1111/irv.12522] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2017] [Indexed: 01/06/2023] Open
Abstract
Influenza control strategies focus on the use of trivalent influenza vaccines containing two influenza A virus subtypes and one of the two circulating influenza type B lineages (Yamagata or Victoria). Mismatches between the vaccine B lineage and the circulating lineage have been regularly documented in many countries, including those in the Asia‐Pacific region. We conducted a literature review with the aim of understanding the relative circulation of influenza B viruses in Asia‐Pacific countries. PubMed and Western Pacific Region Index Medicus were searched for relevant articles on influenza type B published since 1990 in English language for 15 Asia‐Pacific countries. Gray literature was also accessed. From 4834 articles identified, 121 full‐text articles were analyzed. Influenza was reported as an important cause of morbidity in the Asia‐Pacific region, affecting all age groups. In all 15 countries, influenza B was identified and associated with between 0% and 92% of laboratory‐confirmed influenza cases in any one season/year. Influenza type B appeared to cause more illness in children aged between 1 and 10 years than in other age groups. Epidemiological data for the two circulating influenza type B lineages remain limited in several countries in the Asia‐Pacific, although the co‐circulation of both lineages was seen in countries where strain surveillance data were available. Mismatches between circulating B lineages and vaccine strains were observed in all countries with available data. The data suggest that a shift from trivalent to quadrivalent seasonal influenza vaccines could provide additional benefits by providing broader protection.
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Affiliation(s)
- Lance Jennings
- Canterbury District Health Board, Christchurch, New Zealand
| | - Qiu Sue Huang
- WHO National Influenza Centre, Institute of Environmental Science and Research, Porirua, New Zealand
| | - Ian Barr
- WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, VIC, Australia
| | - Ping-Ing Lee
- Department of Pediatrics, National Taiwan University Children's Hospital, Taipei, Taiwan
| | - Woo Joo Kim
- Department of Internal Medicine, Korea University Guro Hospital, Seoul, Korea
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23
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de Boer PT, Kelso JK, Halder N, Nguyen TPL, Moyes J, Cohen C, Barr IG, Postma MJ, Milne GJ. The cost-effectiveness of trivalent and quadrivalent influenza vaccination in communities in South Africa, Vietnam and Australia. Vaccine 2018; 36:997-1007. [PMID: 29373192 PMCID: PMC5805858 DOI: 10.1016/j.vaccine.2017.12.073] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/20/2017] [Accepted: 12/27/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND To inform national healthcare authorities whether quadrivalent influenza vaccines (QIVs) provide better value for money than trivalent influenza vaccines (TIVs), we assessed the cost-effectiveness of TIV and QIV in low-and-middle income communities based in South Africa and Vietnam and contrasted these findings with those from a high-income community in Australia. METHODS Individual based dynamic simulation models were interfaced with a health economic analysis model to estimate the cost-effectiveness of vaccinating 15% of the population with QIV or TIV in each community over the period 2003-2013. Vaccination was prioritized for HIV-infected individuals, before elderly aged 65+ years and young children. Country or region-specific data on influenza-strain circulation, clinical outcomes and costs were obtained from published sources. The societal perspective was used and outcomes were expressed in International$ (I$) per quality-adjusted life-year (QALY) gained. RESULTS When compared with TIV, we found that QIV would provide a greater reduction in influenza-related morbidity in communities in South Africa and Vietnam as compared with Australia. The incremental cost-effectiveness ratio of QIV versus TIV was estimated at I$4183/QALY in South Africa, I$1505/QALY in Vietnam and I$80,966/QALY in Australia. CONCLUSIONS The cost-effectiveness of QIV varied between communities due to differences in influenza epidemiology, comorbidities, and unit costs. Whether TIV or QIV is the most cost-effective alternative heavily depends on influenza B burden among subpopulations targeted forvaccination in addition to country-specific willingness-to-pay thresholds and budgetary impact.
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Affiliation(s)
- Pieter T de Boer
- Unit of Pharmacotherapy, Epidemiology & Economics (PTE2), Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands.
| | - Joel K Kelso
- School of Computer Science and Software Engineering, University of Western Australia, Perth, Australia.
| | - Nilimesh Halder
- School of Computer Science and Software Engineering, University of Western Australia, Perth, Australia.
| | - Thi-Phuong-Lan Nguyen
- Unit of Pharmacotherapy, Epidemiology & Economics (PTE2), Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands; Faculty of Public Health, Thai Nguyen University of Medicine and Pharmacy, Thai Nguyen, Viet Nam.
| | - Jocelyn Moyes
- Centre for Respiratory Disease and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa; School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa.
| | - Cheryl Cohen
- Centre for Respiratory Disease and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa; School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa.
| | - Ian G Barr
- WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, Australia.
| | - Maarten J Postma
- Unit of Pharmacotherapy, Epidemiology & Economics (PTE2), Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands; Institute for Science in Healthy Aging & healthcaRE (SHARE), University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands; Department of Epidemiology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands.
| | - George J Milne
- School of Computer Science and Software Engineering, University of Western Australia, Perth, Australia.
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24
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Ho NT, Thompson C, Nhan LNT, Van HMT, Dung NT, Tran My P, Quang VM, Minh NNQ, Tuan TA, Hung NT, Tuan HM, Vinh Chau NV, Wolbers M, Thwaites GE, Choisy M, Baker S. Retrospective analysis assessing the spatial and temporal distribution of paediatric acute respiratory tract infections in Ho Chi Minh City, Vietnam. BMJ Open 2018; 8:e016349. [PMID: 29358416 PMCID: PMC5780701 DOI: 10.1136/bmjopen-2017-016349] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Acute respiratory tract infections (ARIs) are the leading cause of morbidity and mortality in young children in low/middle-income countries. Using routine hospital data, we aimed to examine the spatial distribution, temporal trends and climatic risk factors of paediatric ARIs in Vietnam. METHODS Data from hospitalised paediatric (<16 years) patients with ARIs residing in Ho Chi Minh City (HCMC) between 2005 and 2010 were retrieved from the two main Children's Hospitals and the Hospital for Tropical Diseases in HCMC. Spatial mapping and time series analysis were performed after disaggregating data into upper respiratory tract infections (URIs) and lower respiratory tract infections (LRIs). RESULTS Over the study period, there were 155 999 paediatric patients admitted with ARIs (33% of all hospital admissions). There were 68 120 URIs (14%) and 87 879 LRIs (19%). The most common diagnoses were acute pharyngitis (28% of all ARI), pneumonia (21%), bronchitis (18%) and bronchiolitis (16%). A significant increasing trend over time was found for both URIs (mean weekly incidence per 1000 population, I=3.12), incidence rate ratio for 1-week increase in time (RR 1.0, 95% CI 1.02 to 1.17) for URI and (I=4.02, RR 1.08 (95% CI 1.006 to 1.16)) for LRI. The weekly URI incidence peaked in May-June and was significantly associated with lags in weekly URI incidence and the average humidity, rainfall and water level. The weekly LRI incidence exhibited significant seasonality (P<0.0001), with an annual peak in September-October and was significantly associated with lags in weekly LRI incidence and lags in weekly average temperature, rainfall and water level. CONCLUSIONS ARIs are a leading cause of childhood hospitalisation in HCMC, Vietnam. The incidence of ARIs was higher in the wet season and in specific HCMC districts. These results may guide health authorities in where and when to effectively allocate resources for the prevention and control of ARIs.
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Affiliation(s)
- Nhan Thi Ho
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
- Pediatrics, Columbia UniversityMedical Center, New York, New York, United States
| | - Corinne Thompson
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Infection Biology, The London School of Hygiene & Tropical Medicine, London, UK
| | | | | | - Nguyen Thanh Dung
- General planning, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Phuc Tran My
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
| | - Vo Minh Quang
- General planning, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | | | - Tran Anh Tuan
- General medicine, Children’s Hospital 1, Ho Chi Minh City, Vietnam
| | | | - Ha Manh Tuan
- General medicine, Children’s Hospital 2, Ho Chi Minh City, Vietnam
| | | | - Marcel Wolbers
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Guy E Thwaites
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Marc Choisy
- Institute of Research and Development, Ho Chi Minh City, Vietnam
| | - Stephen Baker
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
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25
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Structure of general-population antibody titer distributions to influenza A virus. Sci Rep 2017; 7:6060. [PMID: 28729702 PMCID: PMC5519701 DOI: 10.1038/s41598-017-06177-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/09/2017] [Indexed: 12/24/2022] Open
Abstract
Seroepidemiological studies aim to understand population-level exposure and immunity to infectious diseases. Their results are normally presented as binary outcomes describing the presence or absence of pathogen-specific antibody, despite the fact that many assays measure continuous quantities. A population's natural distribution of antibody titers to an endemic infectious disease may include information on multiple serological states - naiveté, recent infection, non-recent infection, childhood infection - depending on the disease in question and the acquisition and waning patterns of immunity. In this study, we investigate 20,152 general-population serum samples from southern Vietnam collected between 2009 and 2013 from which we report antibody titers to the influenza virus HA1 protein using a continuous titer measurement from a protein microarray assay. We describe the distributions of antibody titers to subtypes 2009 H1N1 and H3N2. Using a model selection approach to fit mixture distributions, we show that 2009 H1N1 antibody titers fall into four titer subgroups and that H3N2 titers fall into three subgroups. For H1N1, our interpretation is that the two highest-titer subgroups correspond to recent and historical infection, which is consistent with 2009 pandemic attack rates. Similar interpretations are available for H3N2, but right-censoring of titers makes these interpretations difficult to validate.
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26
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Nguyen HKL, Nguyen SV, Nguyen AP, Hoang PMV, Le TT, Nguyen TC, Hoang HT, Vuong CD, Tran LTT, Le MQ. Surveillance of Severe Acute Respiratory Infection (SARI) for Hospitalized Patients in Northern Vietnam, 2011-2014. Jpn J Infect Dis 2017; 70:522-527. [PMID: 28367882 DOI: 10.7883/yoken.jjid.2016.463] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Severe acute respiratory infections (SARI) are leading causes of hospitalization, morbidity, and mortality in children worldwide. The aim of this study was to identify viral pathogens responsible for SARI in northern Vietnam in the period from 2011 to 2014. Throat swabs and tracheal aspirates were collected from SARI patients according to WHO guidelines. The presence of 13 different viral pathogens (influenza A[H1N1]pdm09; A/H3N2; A/H5; A/H7 and B; para influenza 1,2,3; RSV; HMPV; adeno; severe acute respiratory syndrome-CoV and rhino) was tested by conventional/real-time reverse transcription-polymerase chain reaction. During the study period, 975 samples were collected and tested. More than 30% (32.1%, 313 samples) of the samples showed evidence of infection with influenza viruses, including A/H3N2 (48 samples), A (H1N1) pdm09 (221 samples), influenza B (42 samples), and co-infection of A (H1N1) pdm09 or A/H3N2 and influenza B (2 samples). Other respiratory pathogens were detected in 101 samples, including rhinovirus (73 samples), adenovirus (10 samples), hMPV (9 samples), parainfluenza 3 (5 samples), parainfluenza 2 (3 samples), and RSV (1 sample). Influenza A/H5, A/H7, or SARS-CoV were not detected. Respiratory viral infection, particularly infection of influenza and rhinoviruses, were associated with high rates of SARI hospitalization, and future studies correlating the clinical aspects are needed to design interventions, including targeted vaccination.
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Affiliation(s)
| | - Son Vu Nguyen
- Virology Department, National Institute of Hygiene and Epidemiology
| | | | | | - Thanh Thi Le
- Virology Department, National Institute of Hygiene and Epidemiology
| | - Thach Co Nguyen
- Virology Department, National Institute of Hygiene and Epidemiology
| | - Huong Thu Hoang
- Virology Department, National Institute of Hygiene and Epidemiology
| | - Cuong Duc Vuong
- Virology Department, National Institute of Hygiene and Epidemiology
| | | | - Mai Quynh Le
- Virology Department, National Institute of Hygiene and Epidemiology
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27
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Multiple Viral Infection Detected from Influenza-Like Illness Cases in Indonesia. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9541619. [PMID: 28232948 PMCID: PMC5292373 DOI: 10.1155/2017/9541619] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/22/2016] [Accepted: 12/13/2016] [Indexed: 01/30/2023]
Abstract
Influenza is one of the common etiologies of the upper respiratory tract infection (URTI). However, influenza virus only contributes about 20 percent of influenza-like illness patients. The aim of the study is to investigate the other viral etiologies from ILI cases in Indonesia. Of the 334 samples, 266 samples (78%) were positive at least for one virus, including 107 (42%) cases of multiple infections. Influenza virus is the most detected virus. The most frequent combination of viruses identified was adenovirus and human rhinovirus. This recent study demonstrated high detection rate of several respiratory viruses from ILI cases in Indonesia. Further studies to determine the relationship between viruses and clinical features are needed to improve respiratory disease control program.
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28
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Kamigaki T, Chaw L, Tan AG, Tamaki R, Alday PP, Javier JB, Olveda RM, Oshitani H, Tallo VL. Seasonality of Influenza and Respiratory Syncytial Viruses and the Effect of Climate Factors in Subtropical-Tropical Asia Using Influenza-Like Illness Surveillance Data, 2010 -2012. PLoS One 2016; 11:e0167712. [PMID: 28002419 PMCID: PMC5176282 DOI: 10.1371/journal.pone.0167712] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 11/18/2016] [Indexed: 12/04/2022] Open
Abstract
INTRODUCTION The seasonality of influenza and respiratory syncytial virus (RSV) is well known, and many analyses have been conducted in temperate countries; however, this is still not well understood in tropical countries. Previous studies suggest that climate factors are involved in the seasonality of these viruses. However, the extent of the effect of each climate variable is yet to be defined. MATERIALS AND METHODS We investigated the pattern of seasonality and the effect of climate variables on influenza and RSV at three sites of different latitudes: the Eastern Visayas region and Baguio City in the Philippines, and Okinawa Prefecture in Japan. Wavelet analysis and the dynamic linear regression model were applied. Climate variables used in the analysis included mean temperature, relative and specific humidity, precipitation, and number of rainy days. The Akaike Information Criterion estimated in each model was used to test the improvement of fit in comparison with the baseline model. RESULTS At all three study sites, annual seasonal peaks were observed in influenza A and RSV; peaks were unclear for influenza B. Ranges of climate variables at the two Philippine sites were narrower and mean variables were significantly different among the three sites. Whereas all climate variables except the number of rainy days improved model fit to the local trend model, their contributions were modest. Mean temperature and specific humidity were positively associated with influenza and RSV at the Philippine sites and negatively associated with influenza A in Okinawa. Precipitation also improved model fit for influenza and RSV at both Philippine sites, except for the influenza A model in the Eastern Visayas. CONCLUSIONS Annual seasonal peaks were observed for influenza A and RSV but were less clear for influenza B at all three study sites. Including additional data from subsequent more years would help to ascertain these findings. Annual amplitude and variation in climate variables are more important than their absolute values for determining their effect on the seasonality of influenza and RSV.
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Affiliation(s)
- Taro Kamigaki
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Liling Chaw
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Alvin G. Tan
- Department of Epidemiology and Biostatistics, Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
| | - Raita Tamaki
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Portia P. Alday
- Department of Epidemiology and Biostatistics, Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
| | - Jenaline B. Javier
- Department of Epidemiology and Biostatistics, Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
| | - Remigio M. Olveda
- Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Veronica L. Tallo
- Department of Epidemiology and Biostatistics, Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
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Epidemiological and Virological Characteristics of Influenza in Chongqing, China, 2011-2015. PLoS One 2016; 11:e0167866. [PMID: 27936139 PMCID: PMC5148009 DOI: 10.1371/journal.pone.0167866] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/21/2016] [Indexed: 11/21/2022] Open
Abstract
Background Chongqing is the largest municipality and located in Southwestern of China, with over 30 million registered inhabitants. There are few reports regarding the epidemiology of influenza in Chongqing. The objective of the paper is to explore the epidemiology of influenza in Chongqing, in order to provide scientific basis for prevention and control of influenza. Methodology /Principal Findings From 2011 to 2015, we collected information on influenza-like illness (ILI) patients fulfilling the case definition, and took nasalpharyngeal or throat swabs specimens from ILI cases per week at the 7 sentinel hospitals. Specimens were tested by reverse transcription-polymerase chain reaction(RT-PCR) for influenza. Descriptive epidemiology was applied to analyze the epidemiology and etiology of influenza. A total of 9,696,212 cases were enrolled, of which 111,589 were ILI. Of those 24,868 samples from ILI cases, 13.3% (3,314/24,868) tested positive for influenza virus (65.7% influenza A, 34.1% influenza B, and 0.2% influenza A and B co-infection). Among the influenza A viruses, 71.3% were seasonal influenza A(H3N2) and 28.7% were influenza A(H1N1)pdm09. No cases of seasonal A(H1N1) were detected. The isolation rate was highest in children aged 5–14 years old. Influenza activity consistently peaked during January-March in 2011–2015, and June-July in 2012, 2014 and 2015. Conclusions Influenza is an important public health problem among ILI patients in Chongqing, especially among school-aged children. It might be beneficial to prioritize influenza vaccination for school-aged children and implement the school-based intervention to prevent and mitigating influenza outbreaks in Chongqing, particularly during the seasonal peaks.
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Temporal Patterns of Influenza A and B in Tropical and Temperate Countries: What Are the Lessons for Influenza Vaccination? PLoS One 2016; 11:e0152310. [PMID: 27031105 PMCID: PMC4816507 DOI: 10.1371/journal.pone.0152310] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 03/11/2016] [Indexed: 12/28/2022] Open
Abstract
Introduction Determining the optimal time to vaccinate is important for influenza vaccination programmes. Here, we assessed the temporal characteristics of influenza epidemics in the Northern and Southern hemispheres and in the tropics, and discuss their implications for vaccination programmes. Methods This was a retrospective analysis of surveillance data between 2000 and 2014 from the Global Influenza B Study database. The seasonal peak of influenza was defined as the week with the most reported cases (overall, A, and B) in the season. The duration of seasonal activity was assessed using the maximum proportion of influenza cases during three consecutive months and the minimum number of months with ≥80% of cases in the season. We also assessed whether co-circulation of A and B virus types affected the duration of influenza epidemics. Results 212 influenza seasons and 571,907 cases were included from 30 countries. In tropical countries, the seasonal influenza activity lasted longer and the peaks of influenza A and B coincided less frequently than in temperate countries. Temporal characteristics of influenza epidemics were heterogeneous in the tropics, with distinct seasonal epidemics observed only in some countries. Seasons with co-circulation of influenza A and B were longer than influenza A seasons, especially in the tropics. Discussion Our findings show that influenza seasonality is less well defined in the tropics than in temperate regions. This has important implications for vaccination programmes in these countries. High-quality influenza surveillance systems are needed in the tropics to enable decisions about when to vaccinate.
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Milne GJ, Halder N, Kelso JK, Barr IG, Moyes J, Kahn K, Twine R, Cohen C. Trivalent and quadrivalent influenza vaccination effectiveness in Australia and South Africa: results from a modelling study. Influenza Other Respir Viruses 2016; 10:324-32. [PMID: 26663701 PMCID: PMC4910176 DOI: 10.1111/irv.12367] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2015] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND A modelling study was conducted to determine the effectiveness of trivalent (TIV) and quadrivalent (QIV) vaccination in South Africa and Australia. OBJECTIVES This study aimed to determine the potential benefits of alternative vaccination strategies which may depend on community-specific demographic and health characteristics. METHODS Two influenza A and two influenza B strains were simulated using individual-based simulation models representing specific communities in South Africa and Australia over 11 years. Scenarios using TIV or QIV, with alternative prioritisation strategies and vaccine coverage levels, were evaluated using a country-specific health outcomes process. RESULTS In South Africa, approximately 18% fewer deaths and hospitalisations would be expected to result from the use of QIV compared to TIV over the 11 modelled years (P = 0·031). In Australia, only 2% (P = 0·30) fewer deaths and hospitalisations would result. Vaccinating 2%, 5%, 15% or 20% of the population with TIV using a strategy of prioritising vulnerable age groups, including HIV-positive individuals, resulted in reductions in hospitalisations and mortality of at least 7%, 18%, 57% and 66%, respectively, in both communities. CONCLUSIONS The degree to which QIV can reduce health burden compared to TIV is strongly dependent on the number of years in which the influenza B lineage in the TIV matches the circulating B lineages. Assuming a moderate level of B cross-strain protection, TIV may be as effective as QIV. The choice of vaccination prioritisation has a greater impact than the QIV/TIV choice, with strategies targeting those most responsible for transmission being most effective.
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Affiliation(s)
- George J Milne
- School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia
| | - Nilimesh Halder
- School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia
| | - Joel K Kelso
- School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia
| | - Ian G Barr
- World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza, Melbourne, Vic., Australia
| | - Jocelyn Moyes
- Centre for Respiratory Disease and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Kathleen Kahn
- MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Faculty of Health Science, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Rhian Twine
- MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Faculty of Health Science, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Cheryl Cohen
- Centre for Respiratory Disease and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa.,Faculty of Health Science, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
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Millman AJ, Havers F, Iuliano AD, Davis CT, Sar B, Sovann L, Chin S, Corwin AL, Vongphrachanh P, Douangngeun B, Lindblade KA, Chittaganpitch M, Kaewthong V, Kile JC, Nguyen HT, Pham DV, Donis RO, Widdowson MA. Detecting Spread of Avian Influenza A(H7N9) Virus Beyond China. Emerg Infect Dis 2016; 21:741-9. [PMID: 25897654 PMCID: PMC4412232 DOI: 10.3201/eid2105.141756] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
This virus is unlikely to have spread substantially among humans in Vietnam, Thailand, Cambodia, and Laos. During February 2013–March 2015, a total of 602 human cases of low pathogenic avian influenza A(H7N9) were reported; no autochthonous cases were reported outside mainland China. In contrast, since highly pathogenic avian influenza A(H5N1) reemerged during 2003 in China, 784 human cases in 16 countries and poultry outbreaks in 53 countries have been reported. Whether the absence of reported A(H7N9) outside mainland China represents lack of spread or lack of detection remains unclear. We compared epidemiologic and virologic features of A(H5N1) and A(H7N9) and used human and animal influenza surveillance data collected during April 2013–May 2014 from 4 Southeast Asia countries to assess the likelihood that A(H7N9) would have gone undetected during 2014. Surveillance in Vietnam and Cambodia detected human A(H5N1) cases; no A(H7N9) cases were detected in humans or poultry in Southeast Asia. Although we cannot rule out the possible spread of A(H7N9), substantial spread causing severe disease in humans is unlikely.
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Le TT, Pham TH, Pham TH, Nguyen LKH, Nguyen CT, Hoang VMP, Tran TH, Nguyen VS, Ngo HG, Le QM. Circulation of influenza B lineages in northern Viet Nam, 2007-2014. Western Pac Surveill Response J 2015; 6:17-23. [PMID: 26798557 PMCID: PMC4712529 DOI: 10.5365/wpsar.2015.6.1.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014). METHODS Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates. RESULTS The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014. DISCUSSION The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future.
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Affiliation(s)
- Thi Thanh Le
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | - Thu Hang Pham
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | - Thi Hien Pham
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | | | | | | | - Thu Huong Tran
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | - Vu Son Nguyen
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | - Huong Giang Ngo
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
| | - Quynh Mai Le
- National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam
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Thai PQ, Choisy M, Duong TN, Thiem VD, Yen NT, Hien NT, Weiss DJ, Boni MF, Horby P. Seasonality of absolute humidity explains seasonality of influenza-like illness in Vietnam. Epidemics 2015; 13:65-73. [PMID: 26616043 DOI: 10.1016/j.epidem.2015.06.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Experimental and ecological studies have shown the role of climatic factors in driving the epidemiology of influenza. In particular, low absolute humidity (AH) has been shown to increase influenza virus transmissibility and has been identified to explain the onset of epidemics in temperate regions. Here, we aim to study the potential climatic drivers of influenza-like illness (ILI) epidemiology in Vietnam, a tropical country characterized by a high diversity of climates. We specifically focus on quantifying and explaining the seasonality of ILI. METHODS We used 18 years (1993-2010) of monthly ILI notifications aggregated by province (52) and monthly climatic variables (minimum, mean, maximum temperatures, absolute and relative humidities, rainfall and hours of sunshine) from 67 weather stations across Vietnam. Seasonalities were quantified from global wavelet spectra, using the value of the power at the period of 1 year as a measure of the intensity of seasonality. The 7 climatic time series were characterized by 534 summary statistics which were entered into a regression tree to identify factors associated with the seasonality of AH. Results were extrapolated to the global scale using simulated climatic times series from the NCEP/NCAR project. RESULTS The intensity of ILI seasonality in Vietnam is best explained by the intensity of AH seasonality. We find that ILI seasonality is weak in provinces experiencing weak seasonal fluctuations in AH (annual power <17.6), whereas ILI seasonality is strongest in provinces with pronounced AH seasonality (power >17.6). In Vietnam, AH and ILI are positively correlated. CONCLUSIONS Our results identify a role for AH in driving the epidemiology of ILI in a tropical setting. However, in contrast to temperate regions, high rather than low AH is associated with increased ILI activity. Fluctuation in AH may be the climate factor that underlies and unifies the seasonality of ILI in both temperate and tropical regions. Alternatively, the mechanism of action of AH on disease transmission may be different in cold-dry versus hot-humid settings.
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Affiliation(s)
- Pham Quang Thai
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Hanoi, Viet Nam.
| | - Marc Choisy
- Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Hanoi, Viet Nam; MIVEGEC, University of Montpellier, CNRS 5290, IRD 224, Montpellier, France
| | - Tran Nhu Duong
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Vu Dinh Thiem
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Nguyen Thu Yen
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | | | - Daniel J Weiss
- Spatial Ecology & Epidemiology Group, Department of Zoology, University of Oxford, Oxford, UK
| | - Maciej F Boni
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK; Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam
| | - Peter Horby
- Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Hanoi, Viet Nam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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Otomaru H, Kamigaki T, Tamaki R, Opinion J, Santo A, Daya E, Okamoto M, Saito M, Tallo V, Lupisan S, Suzuki A, Oshitani H. Influenza and other respiratory viruses detected by influenza-like illness surveillance in Leyte Island, the Philippines, 2010-2013. PLoS One 2015; 10:e0123755. [PMID: 25893441 PMCID: PMC4404362 DOI: 10.1371/journal.pone.0123755] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/23/2015] [Indexed: 01/06/2023] Open
Abstract
This study aimed to determine the role of influenza-like illness (ILI) surveillance conducted on Leyte Island, the Philippines, including involvement of other respiratory viruses, from 2010 to 2013. ILI surveillance was conducted from January 2010 to March 2013 with 3 sentinel sites located in Tacloban city, Palo and Tanauan of Leyte Island. ILI was defined as fever ≥38°C or feverish feeling and either cough or running nose in a patient of any age. Influenza virus and other 5 respiratory viruses were searched. A total of 5,550 ILI cases visited the 3 sites and specimens were collected from 2,031 (36.6%) cases. Among the cases sampled, 1,637 (75.6%) were children aged <5 years. 874 (43.0%) cases were positive for at least one of the respiratory viruses tested. Influenza virus and respiratory syncytial virus (RSV) were predominantly detected (both were 25.7%) followed by human rhinovirus (HRV) (17.5%). The age distributions were significantly different between those who were positive for influenza, HRV, and RSV. ILI cases were reported throughout the year and influenza virus was co-detected with those viruses on approximately half of the weeks of study period (RSV in 60.5% and HRV 47.4%). In terms of clinical manifestations, only the rates of headache and sore throat were significantly higher in influenza positive cases than cases positive to other viruses. In conclusion, syndromic ILI surveillance in this area is difficult to detect the start of influenza epidemic without laboratory confirmation which requires huge resources. Age was an important factor that affected positive rates of influenza and other respiratory viruses. Involvement of older age children may be useful to detect influenza more effectively.
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Affiliation(s)
- Hirono Otomaru
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
| | - Taro Kamigaki
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
- * E-mail:
| | - Raita Tamaki
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
| | - Jamie Opinion
- Tacloban City Health Office, Tacloban City, the Philippines
| | - Arlene Santo
- Tanauan Rural Health Unit, Tanauan, the Philippines
| | - Edgard Daya
- Leyte Provincial Health Office, Palo, the Philippines
| | - Michiko Okamoto
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
| | - Mariko Saito
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
- Tohoku-RITM Research Center for Emerging and Reemerging Infections, Muntinlupa City, the Philippines
| | - Veronica Tallo
- Research Institute for Tropical Medicine, Muntinlupa City, the Philippines
| | - Soccoro Lupisan
- Research Institute for Tropical Medicine, Muntinlupa City, the Philippines
| | - Akira Suzuki
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University School of Medicine, Sendai, Japan
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Tran DN, Pham TMH, Ha MT, Hayakawa S, Mizuguchi M, Ushijima H. Molecular epidemiology of influenza A virus infection among hospitalized children in Vietnam during post-pandemic period. J Med Virol 2015; 87:904-12. [PMID: 25648607 PMCID: PMC7166353 DOI: 10.1002/jmv.24143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2014] [Indexed: 12/11/2022]
Abstract
Genetic variability makes influenza virus to escape the immunity and causes yearly epidemics. Monitoring those changes is necessary for vaccine selection. In addition, H3N2 viruses were considered to be seeded from Southeast Asia before spreading globally. This study described the molecular epidemiology of influenza A during the post‐pandemic season 2010–2011 in Vietnam. Nasopharyngeal samples were collected from children with respiratory infections at Children's Hospital 2, Ho Chi Minh City. The HA, NA, M genes were amplified, sequenced and analyzed. Thirty‐five of 1,082 (3.2%) patients were positive for influenza A, including 14 pandemic H1N1 2009 (H1N1pdm09) and 21 H3N2 infections. H3N2 was dominant in the rainy season (May–October 2010) while H1N1pdm09 was dominant in the dry season (November 2010–April 2011). Phylogenetic analysis showed that Vietnamese H1N1pdm09 sequences in 2010–2011 formed the distinct cluster, with other contemporary Asian and 2012‐American sequences, suggesting a possible common ancestor. All were oseltamivir‐sensitive except two strains carrying S247N and D199N in NA which reduced the neuraminidase inhibitor susceptibility. The Vietnamese H3N2 viruses in mid‐2010 belonged to the emerging subclade Perth10/2010, which then spread worldwide in 2011. The Vietnamese influenza viruses were well matched with the Southern Hemisphere vaccine formulation. Mutations at antigenic sites were also identified in these viruses. Surveillance of influenza viruses in tropical countries is important not only for development of their prevention and control strategies but also for earlier identification of the newly emerged strains that may be selected for future vaccine. J. Med. Virol. 87:904–912, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Dinh Nguyen Tran
- Department of Developmental Medical Sciences, School of International Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Department of Pediatrics, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam; Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
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Burmaa A, Kamigaki T, Darmaa B, Nymadawa P, Oshitani H. Epidemiology and impact of influenza in Mongolia, 2007-2012. Influenza Other Respir Viruses 2014; 8:530-7. [PMID: 25043147 PMCID: PMC4181816 DOI: 10.1111/irv.12268] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2014] [Indexed: 11/28/2022] Open
Abstract
Background Mongolia's Health Service began to conduct surveillance for influenza in the 1970s. This surveillance has become more comprehensive over time and now includes 155 sentinel sites in Mongolia. In this study, we analyzed the epidemiological characteristics and impact of influenza using data from influenza surveillance in Mongolia. Materials and methods The data were collected by the National Influenza Center, Mongolia (NIC). Incidence rates of influenza-like illness (ILI) and severe acute respiratory infections (sARI) were calculated as the proportion of the number of ILI and sARI cases to the total population in the studied areas. Nasopharyngeal samples were collected and tested using real-time reverse transcription polymerase chain reaction [(rt)-RT-PCR]. Selected samples negative for influenza were tested for other respiratory pathogens by multiplex rt-RT-PCR. Results Averages of 14·0 ILI and 0·8 sARI episodes per 100 population per year were observed during the five influenza seasons. The highest incidences of influenza associated with ILI and sARI were observed among children 0–4 years old. The number of ILI cases showed a clear seasonality, generally peaking between December and February. In contrast, sARI incidence peaked twice during each season. Influenza B was most prevalent during 2007–2008 and 2011–2012, influenza A (H3N2) during 2010–2011, seasonal A (H1N1) during 2008–2009, and A (H1N1) pdm09 during 2009–2010. Conclusions Additional data on the epidemiology and impact of influenza including socioeconomic impact and vaccine effectiveness are required to develop a national influenza control policy, including a vaccination strategy. Our results provide useful data for developing such a policy.
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Affiliation(s)
- Alexanderyn Burmaa
- National Influenza Center, National Center of Communicable Diseases, Ulaanbaatar, Mongolia
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Thomas RE. Is influenza-like illness a useful concept and an appropriate test of influenza vaccine effectiveness? Vaccine 2014; 32:2143-9. [PMID: 24582634 PMCID: PMC7127078 DOI: 10.1016/j.vaccine.2014.02.059] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/07/2014] [Accepted: 02/12/2014] [Indexed: 11/23/2022]
Abstract
PURPOSE To assess the utility of "influenza-like illness" (ILI) and whether it appropriately tests influenza vaccine effectiveness. PRINCIPAL RESULTS The WHO and CDC definitions of "influenza-like illness" are similar. However many studies use other definitions, some not specifying a temperature and requiring specific respiratory and/or systemic symptoms, making many samples non-comparable. Most ILI studies find less than 25% of cases are RT-PCR-positive, those which test for other viruses and bacteria usually find multiple other pathogens, and most identify no pathogen in about 50% of cases. ILI symptom and symptom combinations do not have high sensitivity or specificity in identifying PCR-positive influenza cases. Rapid influenza diagnostic tests are increasingly used to screen ILI cases and they have low sensitivity and high specificity when compared to RT-PCR in identifying influenza. MAIN CONCLUSIONS The working diagnosis of ILI presumes influenza may be involved until proven otherwise. Health care workers would benefit by renaming the WHO and CDC ILI symptoms and signs as "acute respiratory illness" and also using the WHO acute severe respiratory illness definition if the illness is severe and meets this criterion. This renaming would shift attention to identify the viral and bacterial pathogens in cases and epidemics, identify new pathogens, implement vaccination plans appropriate to the identified pathogens, and estimate workload during the viral season. Randomised controlled trials testing the effectiveness of influenza vaccine require all participants to be assessed by a gold standard (RT-PCR). ILI has no role in measuring influenza vaccine effectiveness. ILI is well established in the literature and in the operational definition of many surveillance databases and its imprecise definition may be inhibiting progress in research and treatment. The current ILI definition could with benefit be renamed "acute respiratory illness," with additional definitions for "severe acute respiratory illness" (SARI) with RT-PCR testing for pathogens to facilitate prevention and treatment.
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Affiliation(s)
- Roger E Thomas
- Department of Family Medicine, Faculty of Medicine, University of Calgary, G012, Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
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Tallo VL, Kamigaki T, Tan AG, Pamaran RR, Alday PP, Mercado ES, Javier JB, Oshitani H, Olveda RM. Estimating influenza outpatients' and inpatients' incidences from 2009 to 2011 in a tropical urban setting in the Philippines. Influenza Other Respir Viruses 2014; 8:159-68. [PMID: 24393336 PMCID: PMC4186463 DOI: 10.1111/irv.12223] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2013] [Indexed: 12/03/2022] Open
Abstract
Objectives Although the public health significance of influenza in regions with a temperate climate has been widely recognized, information on influenza burden in tropical countries, including the Philippines, remains limited. We aimed to estimate influenza incidence rates for both outpatients and inpatients then characterized their demographic features. Design An enhanced surveillance was performed from January 2009 to December 2011 in an urbanized highland city. The influenza-like illness (ILI) surveillance involved all city health centers and an outpatient department of a tertiary government hospital. The severe acute respiratory infection (sARI) surveillance was also conducted with one government and four private hospitals since April 2009. Nasal and/or oropharyngeal swabs were collected and tested for influenza A, influenza B, and respiratory syncytial virus. Results and Conclusions We obtained 5915 specimens from 13 002 ILI cases and 2656 specimens from 10 726 sARI cases throughout the study period. We observed year-round influenza activity with two possible peaks each year. The overall influenza detection rate was 23% in the ILI surveillance and 9% in the sARI surveillance. The mean annual outpatient incidence rate of influenza was 5·4 per 1000 individuals [95% confidence interval (CI), 1·83–12·7], and the mean annual incidence of influenza-associated sARI was 1·0 per 1000 individuals (95% CI, 0·03–5·57). The highest incidence rates were observed among children aged <5 years, particularly those aged 6–23 months. Influenza posed a certain disease burden among inpatients and outpatients, particularly children aged <5 years, in an urbanized tropical city of the Philippines.
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Affiliation(s)
- Veronica L Tallo
- Department of Epidemiology and Biostatistics, Research Institute for Tropical Medicine, Department of Health, Manila, Philippines
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