Background: Global influenza-associated acute respiratory infections contribute to 3-5 million severe illnesses requiring hospitalization annually, with 90% of hospitalizations occurring among children <5 years in developing countries. In Bangladesh, limited availability of nationally representative, robust estimates of influenza-associated hospitalizations limit allocation of resources for prevention and control measures. Methods: This study used data from the Hospital Based Influenza Surveillance (HBIS) system in Bangladesh from 2010-2019 and Healthcare Utilization Surveys to determine hospital utilization patterns in the catchment area. We estimated annual influenza-associated hospitalization numbers and rates for all age groups in Bangladesh using methods outlined by the World Health Organization and adjusted for enrolment, laboratory testing practices, and healthcare seeking behavior. We then estimated national hospitalization rates by multiplying age-specific hospitalization rates with the corresponding annual national census population. Results: Annual influenza-associated hospitalization rates per 100,000 population for all ages ranged from 31 (95% CI: 27-36) in 2011 to 139 (95% CI: 130-149) in 2019. Children <5 years old had the highest rates of influenza-associated hospitalization, ranging from 114 (95% CI: 90-138) in 2011 to 529 (95% CI: 481-578) in 2019, followed by adults aged ≥65 years with rates ranging from 46 (95% CI: 34-57) in 2012 to 252 (95% CI: 213-292) in 2019. The national hospitalization estimates for all ages from 2010-2019 ranged from 47,891 to 236,380 per year. Conclusions: The impact of influenza-associated hospitalizations in Bangladesh may be considerable, particularly for young children and older adults. Targeted interventions, such as influenza vaccination for these age groups, should be prioritized and evaluated.

Since 2004, the U.S. Centers for Disease Control and Prevention (CDC) Influenza Division (ID) has supported seven countries in the Eastern Mediterranean region and the World Health Organization Regional Office for the Eastern Mediterranean to establish and strengthen influenza surveillance. There has been substantial growth in influenza surveillance capacities in the region over two decades that demonstrates commitment by national governments to strengthen national programs and contribute to global influenza surveillance. CDC ID remains committed to continuing support to the region and supporting partners to translate surveillance data into policies and programs effectively.

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.

Background: Despite the WHO recommendation that pregnant women be prioritised for seasonal influenza vaccination, coverage in the Western Pacific Region remains low. Our goal was to provide additional data for the Western Pacific region about the value of maternal influenza vaccination to pregnant women and their families. Methods: We conducted a 16-year retrospective cohort to evaluate risks associated with influenza-associated maternal acute respiratory infection (ARI) in New Zealand. ARI hospitalisations during the May-September influenza season were identified using select ICD-10-AM primary and secondary discharge codes from chapter J00-J99 (diseases of the respiratory system). Cox proportional hazards models were used to calculate crude and adjusted hazard ratios (aHR) and 95% confidence intervals (CI). Results: We identified 822,391 pregnancies among New Zealand residents between 2003 and 2018; 5,095 (0.6%) had >1 associated ARI hospitalisation during the influenza season; these pregnancies were at greater risk of preterm birth (aHR 1.5, 95% CI 1.3-1.7), and low birthweight (aHR 1.7, 95% CI 1.5-2.0) than pregnancies without such hospitalisations. We did not find an association between maternal ARI hospitalisation and fetal death (aHR 1.1, 95% CI 0.6-1.4) during the influenza season. Maternal influenza vaccination was associated with reduced risk of preterm birth (aHR 0.8, 95% CI 0.7-0.9), and low birthweight (aHR 0.9, 95%CI 0.8-0.9), and fetal death (aHR 0.5%, 95% CI 0.3-0.7). Conclusion: In this population-based cohort, being hospitalised for an ARI during the influenza season while pregnant was a risk-factor for delivering a preterm or a low birthweight infant and vaccination reduced this risk.

Objective: To describe the burden of influenza among pregnant women and their young infants. Design: Prospective cohort study. Setting: Rural western Kenya. Population: Pregnant women below 31 weeks of gestation and their infants aged 6 months and below Methods: We conducted weekly follow-up until 6 months postpartum to identify acute respiratory illnesses (ARI). We collected nasal/nasopharyngeal and oropharyngeal swabs from mothers/infants with ARI and tested for influenza A and B using polymerase chain reaction. We calculated incidence of laboratory-confirmed influenza per 1,000 person-months. Main outcome measure: Incidence of medically attended influenza illness among pregnant women and its impact on birth outcomes. Results: During June 2015–May 2020, we enrolled 3,026 pregnant women at a median gestational age of 16 weeks (interquartile range [IQR], 13, 18) and followed 2,550 infants. Incidence of laboratory-confirmed influenza during pregnancy (10.3 episodes per 1,000 person-months [95% CI 8.6–11.8]) was 2-fold higher than in the postpartum period (4.0 [95% CI 2.6–5.5]; p<0.01), and significantly higher among HIV-infected pregnant women (15.6 [95% CI 11.0–20.6] vs. 9.1 [95% CI 7.5–10.8]; p<0.01). Incidence among young infants was 4.4 (95% CI 3.0–5.9) and similar among HIV-exposed and HIV-unexposed infants. Conclusion: Our findings suggest a substantial burden of influenza illnesses during pregnancy, with a higher burden among HIV-infected mothers. Kenyan authorities should consider the value of vaccinating pregnant women, especially if HIV-infected. Funding: This work was supported by funding [Grant number GH002133] from the U.S. CDC, through the Influenza Division. Keywords: Burden, influenza, pregnant women, infants