Influenza‐associated respiratory illness among five cohorts of pregnant women and their young infants (0–6 months), Bangladesh, 2013–2017

BACKGROUND: Pregnant women with their infants are considered at higher risk for influenza‐associated complications, and the World Health Organization (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 are no routine influenza vaccinations in Bangladesh. METHODS: Five annual cohorts (2013–2017) of pregnant women were enrolled from the eight sub‐districts of Bangladesh before the influenza season (May–September); they were 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 these symptoms: cough, rhinorrhea, or difficulty in breathing) among their infants from birth to 6 months of age. We collected nasopharyngeal swabs from ILI and ARI cases, tested by real‐time reverse transcription polymerase chain reaction (rRT‐PCR) for influenza virus (including types and subtypes) and estimated influenza incidence (95% CI)/10000 pregnant women‐months or infant‐months, respectively. RESULTS: We enrolled 9020 pregnant women, followed for 26,709 pregnancy‐months, and detected 1241 ILI episodes. We also followed 8963 infants for 51,518 infant‐months and identified 5116 ARI episodes. Influenza positivity was 23% for ILI and 3% for ARI cases. The overall incidence (2013–2017) of influenza among pregnant women was 158.5/10000 pregnant women‐months (95% CI: 141.4–177.6) and that among infants was 21.9/10000 infant‐months (95% CI: 18.2–26.5). CONCLUSIONS: Although the data was collected more than 5 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.