Influenza surveillance from November 2008 to 2011; including pandemic influenza A(H1N1)pdm09 in Bhutan

Introducing seasonal influenza vaccine in Bhutan: Country experience and achievements

Bhutan successfully introduced multiple vaccines since the establishment of the Vaccine Preventable Disease Program in 1979. Surveillance and subsequent introduction of influenza vaccination became a public health priority for the Ministry of Health following the influenza A(H1N1)pdm09 pandemic. Sentinel surveillance for influenza in Bhutan began in 2008, and a study of severe acute respiratory infection was conducted in 2017, which found the highest influenza burden in children aged <5 years and adults ≥50 years. Following review of surveillance and burden of disease data, the National Technical Advisory Group presented recommendations to Bhutan's Ministry of Health which approved influenza vaccine introduction for all five high-risk groups in the country. Upon the official launch of the program in June 2018, the Vaccine Preventable Disease Program began planning, budgeting, and procurement processes with technical and financial support from the Partnership for Influenza Vaccine Introduction, the United States Centers for Disease Control and Prevention, the Bhutan Health Trust Fund, and the World Health Organization. Influenza vaccination for high-risk groups was integrated into Bhutan's routine immunization services in all health care facilities beginning in November 2019 and vaccinated all populations in 2020 in response to the COVID-19 pandemic. Coverage levels between 2019 and 2022 were highest in children aged 6-24 months (62.5%-96.9%) and lowest in pregnant women (47.7%-62.5%). Bhutan maintained high coverage levels despite the COVID-19 pandemic by continued provision of influenza vaccine services at health centers during lockdowns, conducting communication and sensitization efforts, and using catch-up campaigns. Bhutan's experience with introducing and scaling up the influenza vaccine program contributed to the country's capacity to rapidly deploy its COVID-19 vaccination program in 2021.

Multiplex Real-Time Reverse-Transcription Polymerase Chain Reaction Assays for Diagnostic Testing of Severe Acute Respiratory Syndrome Coronavirus 2 and Seasonal Influenza Viruses: A Challenge of the Phase 3 Pandemic Setting

BACKGROUND

Pandemic coronavirus disease 2019 (COVID-19) disease represents a challenge for healthcare structures. The molecular confirmation of samples from infected individuals is crucial and therefore guides public health decision making. Clusters and possibly increased diffuse transmission could occur in the context of the next influenza season. For this reason, a diagnostic test able to discriminate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from influenza viruses is urgently needed.

METHODS

A multiplex real-time reverse-transcription polymerase chain reaction (PCR) assay was assessed using 1 laboratory protocol with different real-time PCR instruments. Overall, 1000 clinical samples (600 from samples SARS-CoV-2-infected patients, 200 samples from influenza-infected patients, and 200 negative samples) were analyzed.

RESULTS

The assay developed was able to detect and discriminate each virus target and to intercept coinfections. The limit of quantification of each assay ranged between 5 and 10 genomic copy numbers, with a cutoff value of 37.7 and 37.8 for influenza and SARS-CoV-2 viruses, respectively. Only 2 influenza coinfections were detected in COVID-19 samples.

CONCLUSIONS

This study suggests that multiplex assay is a rapid, valid, and accurate method for the detection of SARS-CoV-2 and influenza viruses in clinical samples. The test may be an important diagnostic tool for both diagnostic and surveillance purposes during the seasonal influenza activity period.

Detection of influenza virus in air samples of patient rooms

BACKGROUND

Understanding the transmission and dispersal of influenza virus and respiratory syncytial virus (RSV) via aerosols is essential for the development of preventative measures in hospital environments and healthcare facilities.

METHODS

During the 2017-2018 influenza season, patients with confirmed influenza or RSV infections were enrolled. Room air samples were collected close (0.30 m) to and distant (2.20 m) from patients' heads. Real-time polymerase chain reaction was used to detect and quantify viral particles in the air samples. The plaque assay was used to determine the infectiousness of the detected viruses.

FINDINGS

Fifty-one air samples were collected from the rooms of 29 patients with laboratory-confirmed influenza; 51% of the samples tested positive for influenza A virus (IAV). Among the IAV-positive patients, 65% were emitters (had at least one positive air sample), reflecting a higher risk of nosocomial transmission compared with non-emitters. The majority (61.5%) of the IAV-positive air samples were collected 0.3 m from a patient's head, while the remaining IAV-positive air samples were collected 2.2 m from a patient's head. The positivity rate of IAV in air samples was influenced by distance from the patient's head and day of sample collection after hospital admission. Only three patients with RSV infection were recruited and none of them were emitters.

CONCLUSION

Influenza virus can be aerosolized beyond 1 m in patient rooms, which is the distance considered to be safe by infection control practices. Further investigations are needed to determine the extent of infectivity of aerosolized virus particles.

Detection of influenza virus in air samples of patient rooms

BACKGROUND

Understanding the transmission and dispersal of influenza virus and respiratory syncytial virus (RSV) via aerosols is essential for the development of preventative measures in hospital environments and healthcare facilities.

METHODS

During the 2017-2018 influenza season, patients with confirmed influenza or RSV infections were enrolled. Room air samples were collected close (0.30 m) to and distant (2.20 m) from patients' heads. Real-time polymerase chain reaction was used to detect and quantify viral particles in the air samples. The plaque assay was used to determine the infectiousness of the detected viruses.

FINDINGS

Fifty-one air samples were collected from the rooms of 29 patients with laboratory-confirmed influenza; 51% of the samples tested positive for influenza A virus (IAV). Among the IAV-positive patients, 65% were emitters (had at least one positive air sample), reflecting a higher risk of nosocomial transmission compared with non-emitters. The majority (61.5%) of the IAV-positive air samples were collected 0.3 m from a patient's head, while the remaining IAV-positive air samples were collected 2.2 m from a patient's head. The positivity rate of IAV in air samples was influenced by distance from the patient's head and day of sample collection after hospital admission. Only three patients with RSV infection were recruited and none of them were emitters.

CONCLUSION

Influenza virus can be aerosolized beyond 1 m in patient rooms, which is the distance considered to be safe by infection control practices. Further investigations are needed to determine the extent of infectivity of aerosolized virus particles.

Pneumonia in Bhutanese children: what we know, and what we need to know

BACKGROUND

Pneumonia is the single largest cause of death in under-five children worldwide. We conducted a systematic review to identify the knowledge gaps around childhood pneumonia in Bhutan.

METHODS

We searched PubMed, ScienceDirect and Google scholar from conception to 3rd December 2018, World Health Organization, UNICEF, Bhutan's Ministry of Health and other local databases for relevant reports. We included any report describing pneumonia in Bhutanese children with regards to the burden of the disease, aetiology, related risk factors, clinical and prognostic characteristics, surveillance systems and national preventive strategies. Two review authors identified the records. We summarized the findings narratively.

RESULTS

We included 44 records. Although with notable decreasing trends, pneumonia is still accountable for a high burden and mortality rate in Bhutanese children. The national surveillance system focuses mainly on influenza identification but has recently introduced other viral aetiology to monitor. We found very scarce or no data with regard to the bacterial aetiology, related risk factors and clinico-radiological and prognostic characteristics.

CONCLUSION

There is a dearth of data regarding the epidemiological, microbiological, clinical and radiological characteristics of pneumonia in children in Bhutan, leading to challenges while implementing evidence-based management and effective national preventive strategies.

Etiology of Coinfections in Children with Influenza during 2015/16 Winter Season in Nepal

Acute respiratory infections (ARIs) are one of the major public health problems in developing countries like Nepal. Besides the influenza, several other pathogens are responsible for acute respiratory infection in children. Etiology of infections is poorly characterized at the course of clinical management, and hence empirical antimicrobial agents are used. The objective of this study was to characterize the influenza and other respiratory pathogens by real-time PCR assay. A total of 175 throat swab specimens of influenza-positive cases collected at National Influenza Center, Nepal, during the 2015/16 winter season were selected for detecting other respiratory copathogens. Total nucleic acid was extracted using Pure Link viral RNA/DNA mini kit (Invitrogen), and multiplex RT-PCR assays were performed. Influenza A and B viruses were found in 120 (68.6%) and 55 (31.4%) specimens, respectively, among which coinfections were found in 106 (60.6%) specimens. Among the influenza A-positive cases, 25 (20.8%) were A/H1N1 pdm09 and 95 (79.2%) were A/H3 subtypes. Viruses coinfected frequently with influenza virus in children were rhinovirus (26; 14.8%), respiratory syncytial virus A/B (19; 10.8%), adenovirus (14; 8.0%), coronavirus (CoV)-HKU1 (14; 8.0%), CoV-OC43 (5; 2.9%), CoV-229E (2; 1.1%), metapneumovirus A/B (5; 2.9%), bocavirus (6; 3.4%), enterovirus (5; 2.9%), parainfluenza virus-1 (3; 1.7%), and parainfluenza virus-3 (2; 1.1%). Coinfection of Mycoplasma pneumoniae with influenza virus was found in children (5; 2.8%). Most of the viral infection occurred in young children below 5 years of age. In addition to influenza virus, nine different respiratory pathogens were detected, of which coinfections of rhinovirus and respiratory syncytial virus A/B were predominantly found in children. This study gives us better information on the respiratory pathogen profile and coinfection combinations which are important for diagnosis and treatment of ARIs.

The burden of influenza-associated respiratory hospitalizations in Bhutan, 2015-2016

BACKGROUND

Influenza burden estimates help provide evidence to support influenza prevention and control programs. In this study, we estimated influenza-associated respiratory hospitalization rates in Bhutan, a country considering influenza vaccine introduction.

METHODS

Using real-time reverse transcription-polymerase chain reaction laboratory results from severe acute respiratory infection (SARI) surveillance, we estimated the proportion of respiratory hospitalizations attributable to influenza each month among patients aged <5, 5-49, and ≥50 years in six Bhutanese districts for 2015 and 2016. We divided the sum of the monthly influenza-attributed hospitalizations by the total of the six district populations to generate age-specific rates for each year.

RESULTS

In 2015, 10% of SARI patients tested positive for influenza (64/659) and 18% tested positive (129/736) in 2016. The incidence of influenza-associated hospitalizations among all age groups was 50/100 000 persons (95% confidence interval [CI]: 45-55) in 2015 and 118/100 000 persons (95% CI: 110-127) in 2016. The highest rates were among children <5 years: 182/100 000 (95% CI: 153-210) in 2015 and 532/100 000 (95% CI: 473-591) in 2016. The second highest influenza-associated hospitalization rates were among adults ≥50 years: 110/100 000 (95% CI: 91-130) in 2015 and 193/100 000 (95% CI: 165-221) in 2016.

CONCLUSIONS

Influenza viruses were associated with a substantial burden of severe illness requiring hospitalization especially among children and older adults. These findings can be used to understand the potential impact of seasonal influenza vaccination in these age groups.

Dynamic patterns of circulating influenza virus from 2005 to 2012 in Shandong Province, China

To identify circulating emerging/reemerging viral strains and epidemiological trends, an influenza sentinel surveillance network was established in Shandong Province, China, in 2005. Nasal and/or throat swabs from patients with influenza-like-illness were collected at sentinel hospitals. Influenza viruses were detected by reverse transcription polymerase chain reaction (RT-PCR) or virus isolation. From October 2005 to March 2012, 7763 (21.44 %) of 36,209 swab samples were positive for influenza viruses, including 5221 (67.25 %) influenza A and 2542 (32.75 %) influenza B. While the influenza viruses were detected year-round, their type/subtype distribution varied significantly. Peak influenza activity was observed from November to February. The proportion of laboratory-confirmed influenza cases was highest among participants aged 0-4 years (14.97 %) in the 2005-2009 and 2010-2012 influenza seasons and the positivity rate of influenza A(H1N1)pdm09 was highest in the 15 to 24 year age group during the 2009-2010 influenza season. Genetic analysis of hemagglutinin (HA) and neuraminidase (NA) genes revealed that the viruses matched seasonal influenza vaccine strains in general, with some amino acid mutations. Influenza A(H1N1)pdm09 strains isolated in Shandong Province were characterized by an S203T mutation that is specific to clade 7 isolates. This report illustrates that the Shandong Provincial influenza surveillance system was sensitive in detecting influenza virus variability by season and by genetic composition. This system will help official public health target interventions such as education programs and vaccines.

Analytical Sensitivity Comparison between Singleplex Real-Time PCR and a Multiplex PCR Platform for Detecting Respiratory Viruses

Multiplex PCR methods are attractive to clinical laboratories wanting to broaden their detection of respiratory viral pathogens in clinical specimens. However, multiplexed assays must be well optimized to retain or improve upon the analytic sensitivity of their singleplex counterparts. In this experiment, the lower limit of detection (LOD) of singleplex real-time PCR assays targeting respiratory viruses is compared to an equivalent panel on a multiplex PCR platform, the GenMark eSensor RVP. LODs were measured for each singleplex real-time PCR assay and expressed as the lowest copy number detected 95-100% of the time, depending on the assay. The GenMark eSensor RVP LODs were obtained by converting the TCID50/mL concentrations reported in the package insert to copies/μL using qPCR. Analytical sensitivity between the two methods varied from 1.2-1280.8 copies/μL (0.08-3.11 log differences) for all 12 assays compared. Assays targeting influenza A/H3N2, influenza A/H1N1pdm09, influenza B, and human parainfluenza 1 and 2 were most comparable (1.2-8.4 copies/μL, <1 log difference). Largest differences in LOD were demonstrated for assays targeting adenovirus group E, respiratory syncytial virus subtype A, and a generic assay for all influenza A viruses regardless of subtype (319.4-1280.8 copies/μL, 2.50-3.11 log difference). The multiplex PCR platform, the GenMark eSensor RVP, demonstrated improved analytical sensitivity for detecting influenza A/H3 viruses, influenza B virus, human parainfluenza virus 2, and human rhinovirus (1.6-94.8 copies/μL, 0.20-1.98 logs). Broader detection of influenza A/H3 viruses was demonstrated by the GenMark eSensor RVP. The relationship between TCID50/mL concentrations and the corresponding copy number related to various ATCC cultures is also reported.

Viral Etiology of acute respiratory tract infections in hospitalized children and adults in Shandong Province, China

Background

The dominant viral etiologies responsible for acute respiratory infections (ARIs) are poorly understood, particularly among hospitalized patients. Improved etiological insight is needed to improve clinical management and prevention of ARIs.

Methods

Clinical and demographic information and throat swabs were collected from 607 patients from 2011 to 2013 in Shandong Province, China. Multiplex RT-PCR (SeeplexTM RV detection, Seegene) was performed to detected 12 respiratory viral pathogens.

Results

A total of 607 hospitalized patients were enrolled from 2011 to 2013. Viruses were identified in 35.75 % (217/607) of cases, including 78 influenza virus A and B (IVA and IVB), 47 para-influenza viruses (PIVs), 41 respiratory syncytial virus (RSV) and 38 adenovirus (ADV). For the children under 15 year old, the common detected viruses were influenza viruses, RSV, PIVS and ADV, while the principal respiratory viruses were human coronaviruses (HCoV), PIVs, influenza viruses for the old adults. Co-infections with multiple viruses were detected in 15.67 % of patients. Children under 5 years were more likely to have one or more detectable virus associated with their ARI. The peak of ARI caused by the respiratory viruses occurred in winter.

Conclusion

This study demonstrated respiratory viruses were the major cause of hospitalized ARI patients in Shandong Province, influenza virus was the most common detected, RSV was the highest incidence among the young children (≤5 years). These findings also gave a better understand of virus distribution among different age and seasons, which help to consider potential therapeutic approaches and develop effective prevention strategies for respiratory virus infection.

Global burden of influenza as a cause of cardiopulmonary morbidity and mortality

Severe acute respiratory infections, including influenza, are a leading cause of cardiopulmonary morbidity and mortality worldwide. Until recently, the epidemiology of influenza was limited to resource-rich countries. Emerging epidemiological reports characterizing the 2009 H1N1 pandemic, however, suggest that influenza exerts an even greater toll in low-income, resource-constrained environments where it is the cause of 5% to 27% of all severe acute respiratory infections. The increased burden of disease in this setting is multifactorial and likely is the result of higher rates of comorbidities such as human immunodeficiency virus, decreased access to health care, including vaccinations and antiviral medications, and limited healthcare infrastructure, including oxygen therapy or critical care support. Improved global epidemiology of influenza is desperately needed to guide allocation of life-saving resources, including vaccines, antiviral medications, and direct the improvement of basic health care to mitigate the impact of influenza infection on the most vulnerable populations.