Unchanged severity of influenza A(H1N1)pdm09 infection in children during first postpandemic season

Different populations of A(H1N1)pdm09 viruses in a patient with hemolytic-uremic syndrome

Respiratory viral infections may have different impacts ranging from infection without symptoms to severe disease or even death though the reasons are not well characterized. A patient (age group 5-15 years) displaying symptoms of hemolytic uremic syndrome died one day after hospitalization. qPCR, next generation sequencing, virus isolation, antigenic characterization, resistance analysis was performed and virus replication kinetics in well-differentiated airway cells were determined. Autopsy revealed hemorrhagic pneumonia as major pathological manifestation. Lung samples harbored a large population of A(H1N1)pdm09 viruses with the polymorphism H456H/Y in PB1 polymerase. The H456H/Y viruses replicated much faster to high viral titers than upper respiratory tract viruses in vitro. H456H/Y-infected air-liquid interface cultures of differentiated airway epithelial cells did reflect a more pronounced loss of ciliated cells. A different pattern of virus quasispecies was found in the upper airway samples where substitution S263S/F (HA1) was observed. The data support the notion that viral quasispecies had evolved locally in the lung to support high replicative fitness. This change may have initiated further pathogenic processes leading to rapid dissemination of inflammatory mediators followed by development of hemorrhagic lung lesions and fatal outcome.

Characteristics and Results of Hospital Admission Caused by Influenza Virus Infections in Children under 5 Years Old

AIMS

The influenza virus is an infectious disease with acute respiratory tract infections, caused secondary bacterial infections and death. In this study, we aimed to determine which predictors were associated with the need for high-flow nasal cannula oxygen therapy (HFNC) and transition to intensive care for influenza virus and also to compare single viral pathogens with multiple ones.

METHODS

Inpatients under the age of 5 with influenza virus-related respiratory tract infections between November 2015 and March 2019 were included in the study. Demographic features, comorbidities, symptoms, secondary bacterial infection, need for HFNC and pediatric intensive care unit and respiratory support system, length of hospital stay, polymerase chain reaction tests were recorded.

RESULTS

A total of 93 patients were included in the study. It was determined that 53.8% of the cases were male and 84.9% were under the age of 2. Comorbidities were present in 50.5% of the cases. Secondary bacterial pneumonia developed in 56.9% of the cases. Patients with secondary bacterial pneumonia had higher PICU need, HFNC need and hospital stay (p = 0.014, p ≤ 0.001 and p ≤ 0.001, respectively). Patients with comorbidity had longer hospital stays and a higher need for HFNC (p ≤ 0.001 and p = 0.001, respectively).

CONCLUSIONS

In this study, it was determined that especially comorbidity and secondary bacterial infection aggravated the clinical treatment of hospitalized patients. Therefore, it was concluded that patients with comorbidity should be followed closely and secondary bacterial pneumonia should be recognized and treated early.

Viral detection profile in children with severe acute respiratory infection

Objectives

The role of viral co-detection in children with severe acute respiratory infection is not clear. We described the viral detection profile and its association with clinical characteristics in children admitted to the Pediatric Intensive Care Unit (PICU) during the 2009 influenza A(H1N1) pandemic.

Method

Longitudinal observational retrospective study, with patients aged 0–18 years, admitted to 11 PICUs in Rio de Janeiro, with suspected H1N1 infection, from June to November, 2009. The results of respiratory samples which were sent to the Laboratory of Fiocruz/RJ and clinical data extracted from specific forms were analyzed.

Results

Of 71 samples, 38% tested positive for H1N1 virus. Of the 63 samples tested for other viruses, 58 were positive: influenza H1N1 (43.1% of positive samples), rhinovirus/enterovirus (41.4%), respiratory syncytial vírus (12.1%), human metapneumovirus (12.1%), adenovirus (6.9%), and bocavirus (3.5%). Viral codetection occured in 22.4% of the cases. H1N1-positive patients were of a higher median age, had higher frequency of fever, cough and tachypnea, and decreased leukometry when compared to H1N1-negative patients. There was no difference in relation to severity outcomes (number of organic dysfunctions, use of mechanical ventilation or amines, hospital/PICU length of stay or death). Comparing the groups with mono-detection and co-dection of any virus, no difference was found regarding the association with any clinical variable.

Conclusions

Other viruses can be implicated in SARI in children. The role of viral codetection has not yet been completely elucidated.

Characteristics and outcome of ill critical patients with influenza A infection

INTRODUCTION

To describe all patients admitted to Tunisian intensive care unit with a diagnosis of influenza A/H1N1 virus infection after the 2009 influenza pandemic and to analyse their characteristics, predictors of complications and outcome.

METHODS

All patients with influenza > 18-years-old hospitalized to the ICU department of Tunisian University hospital of Sousse, between December 1, 2009 and March 31, 2016, with a positive influenza A/H1N1/09 reverse transcriptase polymerase chain reaction (RT-PCR) from a nasopharyngeal specimen were included, were included.

RESULTS

40 cases were admitted to intensive care units. During the reporting period, 22 deaths in intensive care units (55%) were reported, the median age was 53 years (IQR 37-61), 24 (61%) were male, The median scores SAPS II and SOFA were respectively 29 (IQR 23-36) and 6 (IQR 3-10), 27% had chronic obstructive pulmonary disease (COPD), 33.3% diabetic and no patients were vaccinated against influenza A. The cause of admission was in 72.5% of the cases was hypoxemic pneumonae. By using a logistic regression, we found after adjustment to age, that acute respiratory distress syndrome (ARDS) (OR = 27; 95%CI: 3.62-203.78) was the only factor significantly associated with severe outcomes of the cases.

CONCLUSION

Patients in the first post pandemic season were significantly older and more frequently had underlying medical conditions. Multivariate analysis showed that older male patients with chronic lung disease were at increased risk for a severe clinical outcome.

Molecular and epidemiological analysis of pandemic and post-pandemic influenza A(H1N1)pdm09 virus from central India

Influenza A(H1N1)pdm09 virus pandemic struck India in 2009 and continues to cause outbreaks in its post-pandemic phase. Diminutive information is available about influenza A(H1N1)pdm09 from central India. This observational study presents epidemiological and molecular findings for the period of 6 years. Throat swab samples referred from districts of Madhya Pradesh were subjected to diagnosis of influenza A(H1N1)pdm09 following WHO guidelines. Clinical and epidemiological data were recorded and analyzed. Hemagglutinin (HA) gene sequencing and phylogenetic analysis were performed. The H275Y mutation responsible for antiviral resistance was tested using allelic real-time RT-PCR. Out of 7365 tested samples, 2406 (32.7%) were positive for influenza A(H1N1)pdm09, of which 363 (15.08%) succumbed to infection. Significant trends were observed in positivity (χ²  = 50.8; P < 0.001) and mortality (χ²  = 24.4; P < 0.001) with increasing age. Mutations having clinical and epidemiological importance were detected. Phylogenetic analysis of HA gene sequences revealed that clade 7, 6A, and 6B viruses were in circulation. Oseltamivir resistance was detected in three fatal cases. Influenza A(H1N1)pdm09 viruses having genetic diversity were detected from central India and continues to be a concern for public health. This study highlights the need of year-round monitoring by establishment of strong molecular and clinical surveillance program.

[Influenza and community acquired pneumonia in German primary care]

Influenza and community-acquired pneumonia (CAP) impose a considerable annual burden on the German primary care system. Yet there is a lack of epidemiological data from the country's outpatient sector on groups at risk as well as on the complications of these diseases.The Robert Koch Institute (RKI) initiated the study to identify population groups at increased risk for influenza or CAP as well as related comorbidities and sequelae. We present the methodology of the study and the descriptive analysis of the patients.ICD-10-based data was collected in 89 primary health care practices between January 2012 and April 2015 using a data extraction tool developed on behalf of the RKI. Case-based anonymized information was recorded for all patients in whom influenza, CAP or other acute respiratory infections (ARI) were diagnosed. For each patient information on all diagnoses including the date were retrospectively and prospectively collected (each for six months) as well as age, sex and influenza vaccination.Data on 156,803 patients with ARI was collected, of them 7909 patients with influenza (within influenza waves) and 8528 patients with CAP diagnoses. Influenza diagnoses showed a strong seasonal pattern and captured annual influenza waves in Germany. Of the influenza cases 1.6 % had a following diagnosis of CAP within 30 days. Age-specific prevalence of chronic diseases such as asthma and diabetes was significantly higher in the study population as compared to the German population.The developed tool delivers in a standardized fashion ICD-10-coded epidemiological data on population-based burden of influenza and CAP in Germany. As the descriptive analysis showed, the collected dataset is a reliable and solid basis for the further investigations of the study questions.

Performance of a Taqman Assay for Improved Detection and Quantification of Human Rhinovirus Viral Load

Human rhinovirus (HRV) is the major aetiology of respiratory tract infections. HRV viral load assays are available but limitations that affect accurate quantification exist. We developed a one-step Taqman assay using oligonucleotides designed based on a comprehensive list of global HRV sequences. The new oligonucleotides targeting the 5′-UTR region showed high PCR efficiency (E = 99.6%, R² = 0.996), with quantifiable viral load as low as 2 viral copies/μl. Assay evaluation using an External Quality Assessment (EQA) panel yielded a detection rate of 90%. When tested on 315 human enterovirus-positive specimens comprising at least 84 genetically distinct HRV types/serotypes (determined by the VP4/VP2 gene phylogenetic analysis), the assay detected all HRV species and types, as well as other non-polio enteroviruses. A commercial quantification kit, which failed to detect any of the EQA specimens, produced a detection rate of 13.3% (42/315) among the clinical specimens. Using the improved assay, we showed that HRV sheds in the upper respiratory tract for more than a week following acute infection. We also showed that HRV-C had a significantly higher viral load at 2–7 days after the onset of symptoms (p = 0.001). The availability of such assay is important to facilitate disease management, antiviral development, and infection control.

Continued high incidence of children with severe influenza A(H1N1)pdm09 admitted to paediatric intensive care units in Germany during the first three post-pandemic influenza seasons, 2010/11-2012/13

BACKGROUND

Previous influenza surveillance at paediatric intensive care units (PICUs) in Germany indicated increased incidence of PICU admissions for the pandemic influenza subtype A(H1N1)pdm09. We investigated incidence and clinical characteristics of influenza in children admitted to PICUs during the first three post-pandemic influenza seasons, using active screening.

METHODS

We conducted a prospective surveillance study in 24 PICUs in Bavaria (Germany) from October 2010 to September 2013. Influenza cases among children between 1 month and 16 years of age admitted to these PICUs with acute respiratory infection were confirmed by PCR analysis of respiratory secretions.

RESULTS

A total of 24/7/20 influenza-associated PICU admissions were recorded in the post-pandemic seasons 1/2/3; incidence estimates per 100,000 children were 1.72/0.76/1.80, respectively. Of all 51 patients, 80% had influenza A, including 65% with A(H1N1)pdm09. Influenza A(H1N1)pdm09 was almost absent in season 2 (incidence 0.11), but dominated PICU admissions in seasons 1 (incidence 1.35) and 3 (incidence 1.17). Clinical data was available for 47 influenza patients; median age was 4.8 years (IQR 1.6-11.0). The most frequent diagnoses were influenza-associated pneumonia (62%), bronchitis/bronchiolitis (32%), secondary bacterial pneumonia (26 %), and ARDS (21%). Thirty-six patients (77 %) had underlying medical conditions. Median duration of PICU stay was 3 days (IQR 1-11). Forty-seven per cent of patients received mechanical ventilation, and one patient (2%) extracorporeal membrane oxygenation; 19% were treated with oseltamivir. Five children (11%) had pulmonary sequelae. Five children (11%) died; all had underlying chronic conditions and were infected with A(H1N1)pdm09. In season 3, patients with A(H1N1)pdm09 were younger than in season 1 (p = 0.020), were diagnosed more often with bronchitis/bronchiolitis (p = 0.004), and were admitted to a PICU later after the onset of influenza symptoms (p = 0.041).

CONCLUSIONS

Active screening showed a continued high incidence of A(H1N1)pdm09-associated PICU admissions in the post-pandemic seasons 1 and 3, and indicated possible underestimation of incidence in previous German studies. The age shift of severe A(H1N1)pdm09 towards younger children may be explained by increasing immunity in the older paediatric population. The high proportion of patients with underlying chronic conditions indicates the importance of consistent implementation of the current influenza vaccination recommendations for risk groups in Germany.

Effectiveness of non-pharmaceutical measures in preventing pediatric influenza: a case-control study

BACKGROUND

Hygiene behavior plays a relevant role in infectious disease transmission. The aim of this study was to evaluate non-pharmaceutical interventions (NPI) in preventing pediatric influenza infections.

METHODS

Laboratory confirmed influenza cases occurred during 2009-10 and 2010-11 seasons matched by age and date of consultation. NPI (frequency of hand washing, alcohol-based hand sanitizer use and hand washing after touching contaminated surfaces) during seven days prior to onset of symptoms were obtained from parents of cases and controls.

RESULTS

Cases presented higher prevalence of underlying conditions such as pneumonia [OR = 3.23; 95% CI: 1.38-7.58 p = 0.007], asthma [OR = 2.45; 95% CI: 1.17-5.14 p = 0.02] and having more than 1 risk factor [OR = 1.67; 95% CI: 0.99-2.82 p = 0.05]. Hand washing more than 5 times per day [aOR = 0.62; 95% CI: 0.39-0.99 p = 0.04] was the only statistically significant protective factor. When considering two age groups (pre-school age 0-4 yrs and school age 5-17) yrs , only the school age group showed a negative association for influenza infection for both washing more than 5 times per day [aOR = 0.47; 95% CI: 0.22-0.99 p = 0.04] and hand washing after touching contaminated surfaces [aOR = 0.19; 95% CI: 0.04-0.86 p = 0.03].

CONCLUSION

Frequent hand washing should be recommended to prevent influenza infection in the community setting and in special in the school age group.

Epidemiology of influenza virus types and subtypes in South Africa, 2009-2012

Patient age and co-infections, but not disease severity, were associated with virus type and subtype.

To determine clinical and epidemiologic differences between influenza caused by different virus types and subtypes, we identified patients and tested specimens. Patients were children and adults hospitalized with confirmed influenza and severe acute respiratory illness (SARI) identified through active, prospective, hospital-based surveillance from 2009–2012 in South Africa. Respiratory specimens were tested, typed, and subtyped for influenza virus by PCR. Of 16,005 SARI patients tested, 1,239 (8%) were positive for influenza virus. Patient age and co-infections varied according to virus type and subtype, but disease severity did not. Case-patients with influenza B were more likely than patients with influenza A to be HIV infected. A higher proportion of case-patients infected during the first wave of the 2009 influenza pandemic were 5–24 years of age (19%) than were patients infected during the second wave (9%). Although clinical differences exist, treatment recommendations do not differ according to subtype; prevention through vaccination is recommended.

Influenza in hospitalized children in Ireland in the pandemic period and the 2010/2011 season: risk factors for paediatric intensive-care-unit admission

Influenza causes significant morbidity and mortality in children. This study's objectives were to describe influenza A(H1N1)pdm09 during the pandemic, to compare it with circulating influenza in 2010/2011, and to identify risk factors for severe influenza defined as requiring admission to a paediatric intensive care unit (PICU). Children hospitalized with influenza during the pandemic were older, and more likely to have received antiviral therapy than children hospitalized during the 2010/2011 season. In 2010/2011, only one child admitted to a PICU with underlying medical conditions had been vaccinated. The risk of severe illness in the pandemic was higher in females and those with underlying conditions. In 2010/2011, infection with influenza A(H1N1)pdm09 compared to other influenza viruses was a significant risk factor for severe disease. An incremental relationship was found between the number of underlying conditions and PICU admission. These findings highlight the importance of improving low vaccination uptake and increasing the use of antivirals in vulnerable children.

Changes in severity of influenza A(H1N1)pdm09 infection from pandemic to first postpandemic season, Germany

We studied risk factors for a severe clinical outcome in hospitalized patients with laboratory-confirmed influenza A(H1N1)pdm09 infection at the University Hospital Heidelberg in the pandemic and first postpandemic seasons. We identified 102 patients in 2009–10 and 76 in 2010–11. The proportion of severely diseased patients dramatically increased from 14% in 2009–10 to 46% in 2010–11 as did the mortality rate (5%–12%). Patients in the first postpandemic season were significantly older (38 vs. 18 years) and more frequently had underlying medical conditions (75% vs. 51%). Overall, 50 patients (28%) had a severe clinical outcome, resulting in 14 deaths. Multivariate analysis showed that older male patients with chronic lung disease were at increased risk for a severe clinical outcome. In summary, the proportion of patients with severe disease and fatal cases increased in the postpandemic season. Therefore, patients with suspected infections should be promptly identified and receive early treatment.

Differential use of antivirals for treatment of patients with influenza A(H1N1)pdm09 in Germany

Background

The World Health Organization recommends early antiviral treatment for patients with severe influenza illness or those at increased risk for severe illness.

Objectives

The aim of this study was to determine the proportion of cases with laboratory‐confirmed A(H1N1)pdm09 infection that have been treated with antivirals in Germany during the pandemic (H1N1) 2009 and to investigate factors associated with the use of antivirals.

Methods

We analyzed cases with laboratory‐confirmed A(H1N1)pdm09 infection notified to national health authorities in Germany between week 29/2009 and week 17/2010 using multivariable logistic regression. Severity of disease was defined by pneumonia or death.

Results and conclusions

Of 160 804 cases with laboratory‐confirmed A(H1N1)pdm09 infection, 22% were treated with antivirals. Cases with severe disease were more likely to be treated with antivirals than cases without severe disease (odds ratio = 1·66; 95% confidence interval: 1·46–1·89). In the group with at least one underlying medical condition, only children aged between 1 and 4 years had significant lower odds for receiving antiviral treatment compared with cases in the age group 15 to 49 years (odds ratio = 0·75; 95% confidence interval: 0·6–0·94). In conclusion, the implementation of international recommendations on use of antivirals differed according to the age of patients in Germany during the pandemic (H1N1) 2009. This indicates that the potential of antivirals to prevent severe influenza might not have been fully exhausted. The reasons leading to the observed differences in patient management need to be investigated.

Clinical characteristics and outcomes in hospitalized patients with respiratory viral co-infection during the 2009 H1N1 influenza pandemic

Background

The clinical consequences of co-infection with two or more respiratory viruses are poorly understood. We sought to determine if co-infection with pandemic 2009–2010 influenza A H1N1 (pH1N1) and another respiratory virus was associated with worse clinical outcomes.

Methods

A retrospective cohort study was performed of all hospitalized patients with a positive respiratory viral panel (RVP) for two or more viruses within 72 hours of admission at our institution from October 2009 to December 2009. We compared patients infected with one respiratory virus to those with respiratory viral co-infection.

Results

We identified 617 inpatients with a positive RVP sample with a single virus and 49 inpatients with a positive RVP sample for two viruses (i.e. co-infection). Co-infected patients were significantly younger, more often had fever/chills, tachypnea, and they more often demonstrated interstitial opacities suggestive of viral pneumonia on the presenting chest radiograph (OR 7.5, 95% CI 3.4–16.5). The likelihood of death, length of stay, and requirement for intensive care unit level of care were similar in both groups, but patients with any respiratory virus co-infection were more likely to experience complications, particularly treatment for a secondary bacterial pneumonia (OR 6.8, 95% CI 3.3–14.2). Patients co-infected with pH1N1 and another respiratory virus were more likely to present with chest radiograph changes suggestive of a viral pneumonia, compared to mono-infection with pH1N1 (OR 16.9, 95% CI 4.5–62.7). By logistic regression using mono-infection with non-PH1N1 viruses as the reference group, co-infection with pH1N1 was the strongest independent predictor of treatment for a secondary bacterial pneumonia (OR 17.8, 95% CI 6.7–47.1).

Conclusion

Patients with viral co-infection, particularly with pH1N1, were more likely to have chest radiograph features compatible with a viral pneumonia and complications during their hospital course, particularly treatment for secondary bacterial pneumonia. Despite this, co-infection was not associated with ICU admission.