Background: Recent evidences reported that co-infection with SARS-CoV-2 and Influenza virus is common. We explored hospital-based influenza surveillance (HBIS) data during the COVID-19 pandemic. Methods: We analyzed data from March to December 2020 among patients admitted with severe acute respiratory infections (SARI) defined as subjective or measured fever of ≥ 38 C° and cough with onset within the last ten days. Physicians recorded patients’ demographic, clinical, and laboratory information and obtained nasopharyngeal and oropharyngeal swabs to test for influenza virus and SARS-CoV-2 by rRT-PCR. Results: We enrolled 1,986 SARI case-patients with median age of 28 years (IQR: 1.2 ­ 53 years), and 67.6% were male. Among SARI case-patients, 285 (14.3%) were infected with SARS-CoV-2 and 175 (8.8%) infected with influenza virus. Only five (0.3%) SARI patients were co-infected with SARS-CoV-2 and influenza virus. Difficulty breathing (83% vs. 77%, p=0.024) and sore throat (26% vs. 17%, p<0.001) were more likely to be present in SARS-CoV-2-infected SARI patients. SARI case-patients with diabetes and hypertension were more likely (14% vs. 6%, p<0.001 and 27% vs. 12%, p<0.001 respectively) to be infected with SARS-CoV-2 virus than those without co-morbidities. Influenza virus remained undetectable during the first 14 weeks of the 20 weeks (May to September) of peak influenzacirculation period in Bangladesh. Conclusions: Our findings suggest that co-infection with SARS-CoV-2 and influenza virus was not very common together with nonappearance of the influenza virus during most of the peak influenza period in Bangladesh during COVID-19 pandemic. Future studies are warranted for further exploration.

Background We explored whether hospital-based surveillance is useful in detecting severe acute respiratory infection (SARI) clusters and how often these events result in outbreak investigation and community mitigation. Methods During May 2009– December 2020, physicians at 14 sentinel hospitals prospectively identified SARI clusters (i.e., ≥2 SARI cases who developed symptoms ≤10 days of each other and lived <30 minute walk or <3 km from each other). Oropharyngeal and nasopharyngeal swabs were tested for influenza and other respiratory viruses by rRT-PCR. We describe the demographic of persons within clusters, laboratory results, and outbreak investigations. Results Physicians identified 464 clusters comprising 1,427 SARI cases (range 0–13 clusters per month). Sixty percent of clusters had three, 23% had 2, and 17% had ≥4 cases. Their median age was 2 years (interquartile [IQR] 0.4–25) and 63% were male. Laboratory results were available for the 464 clusters a median 9 days (IQR = 6–13 days) after cluster identification. Less than one in five clusters had cases that tested positive for the same virus: RSV in 58 (13%), influenza viruses in 24 (5%), HMPV in 5 (1%), HPIV in 3 (0.6%), adenovirus in 2 (0.4%). While 102/464 (22%) had poultry exposure, none tested positive for influenza A(H5N1) or A(H7N9). None of the 464 clusters led to field deployments for outbreak response. Conclusions For 11 years, none of the hundreds of identified clusters led to emergency response. The value of this event-based surveillance might be improved by seeking larger clusters, with stronger epidemiologic ties or decedents.

Pregnant women with their infants are considered at higher risk for influenza-associated complications, and the WHO recommends influenza vaccination during pregnancy to protect them, including their infants (0-6 months). There are limited data on the influenza burden among pregnant women and their infants (0-6 months), and there is no routine influenza vaccination in Bangladesh. Five annual cohorts (2013-2017) of pregnant women were enrolled from 8 sub-districts of Bangladesh before the influenza season (May-September); contacted weekly to identify new onset of influenza-like illness (ILI) (subjective or measured fever and cough) and acute respiratory illness (ARI) (at least two of: cough, rhinorrhea, or difficulty breathing) among their infants from birth to 6 months of age. We collected nasopharyngeal swabs from ILI and ARI cases, tested by rRT-PCR for influenza virus (including types and subtypes) and estimated influenza incidence (95% CI) /10,000 pregnancy-months or infant-months, respectively. We enrolled 9,020 pregnant women, followed for 26,709 pregnancy-months and detected 1,241 ILI episodes. We also followed 8,963 infants for 51,518 infant-months and identified 5,116 ARI episodes. Influenza positivity was 23% for ILI and 3% for ARI cases. The overall incidence (2013-2017) of influenza among pregnant women was 158.5/10,000 pregnancy-months (95% CI: 141.4-177.6), and that among infants was 21.9/10,000 infant-months (95% CI: 18.2-26.5). Although the data was collected more than five years ago, as the only baseline data, our findings illustrate evidence of influenza burden among pregnant women and infants (0-6 months) which may support preventive policy decisions in Bangladesh.

In this report we reported the sero-prevalence of West Nile virus among the resident and migratory wild birds from different locations of Bangladesh. 48 birds (48/888, 5.4%, CI 0.04-0.07) were found sero-positive for WNV antibody.

West Nile virus (WNV) is a vector-borne zoonotic disease maintained in a sylvatic cycle involving mosquito vectors and birds. To detect West Nile virus (WNV) and other flavivirus infections in wild resident and migratory birds, we tested 184 samples from 19 identified species within nine families collected during 2012-2016 from four districts in Bangladesh. We tested serum samples for the immunoglobulin G (IgG) antibody to WNV using competitive Enzyme-Linked Immunosorbent Assay (c-ELISA), whereas tracheal and cloacal swabs subjected to consensus PCR for the detection of the flavivirus RNA. Overall, 11.9% (n=22; 95% CI: 0.07-0.16) samples were seropositive, including 15.9% migratory wild birds and 10.7% resident wild birds. Tufted duck showed 28.5% sero-positivity, whereas crows showed 12.5% sero-positivity. None of the swab samples was positive for flavivirus RNA infection. These study findings suggest that wild birds of Bangladesh may carry WNV. We recommend continued surveillance for early detection and to better understand the epidemiology of WNV and other flavivirus circulation in both birds and mosquitoes in Bangladesh.