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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, the inadequate availability of nationally representative, robust estimates of influenza‐associated hospitalizations limits 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 to 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 WHO methods, adjusted for a 6‐day‐a‐week enrollment schedule, selective testing of specimens from children under five, and healthcare‐seeking behavior, based on the proportion of symptomatic community participants seeking healthcare within the past week. 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 during 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. [ABSTRACT FROM AUTHOR]

Annual circulation of influenza viruses causes substantial disease and death worldwide, disproportionately affecting young children and older adults (2,2). Globally, influenza causes [approximately equal to] 9.4 million hospitalizations each year [...]

Background Annual influenza vaccination is recommended for older adults but repeated vaccination with standard-dose influenza vaccine has been linked to reduced immunogenicity and effectiveness, especially against A(H3N2) viruses. Methods Community-dwelling Hong Kong adults aged 65–82 years were randomly allocated to receive 2017–2018 standard-dose quadrivalent, MF59-adjuvanted trivalent, high-dose trivalent, and recombinant-HA quadrivalent vaccination. Antibody response to unchanged A(H3N2) vaccine antigen was compared among participants with and without self-reported prior year (2016–2017) standard-dose vaccination. Results Mean fold rise (MFR) in antibody titers from day 0 to day 30 by hemagglutination inhibition and virus microneutralization assays were lower among 2017–2018 standard-dose and enhanced vaccine recipients with (range, 1.7–3.0) versus without (range, 4.3–14.3) prior 2016–2017 vaccination. MFR was significantly reduced by about one-half to four-fifths for previously vaccinated recipients of standard-dose and all 3 enhanced vaccines (β range,.21–.48). Among prior-year vaccinated older adults, enhanced vaccines induced higher 1.43 to 2.39-fold geometric mean titers and 1.28 to 1.74-fold MFR versus standard-dose vaccine by microneutralization assay. Conclusions In the context of unchanged A(H3N2) vaccine strain, prior-year vaccination was associated with reduced antibody response among both standard-dose and enhanced influenza vaccine recipients. Enhanced vaccines improved antibody response among older adults with prior-year standard-dose vaccination. [ABSTRACT FROM AUTHOR]

Seasonal influenza contributes substantially to acute respiratory disease in Indonesia and across the world. Influenza virus causes [approximately equal to] 3-5 million cases of severe illness (1) and [approximately equal [...]

Snce December 2016, the number of human infections vith avian influenza A(H7N9) virus in China has increased markedly (1,2), prompting concerns of pandemic influenza. Early signals of greater human-to-human transmissibility [...]

Since the first human infections with avian influenza A(H7N9) virus were identified in early 2013 (1), mainland China has experienced 5 epidemics of human infections with A(H7N9) virus (2). As [...]

Background Although most adults infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) fully recover, a proportion have ongoing symptoms, or post-COVID conditions (PCC), after infection. The objective of this analysis was to estimate the number of United States (US) adults with activity-limiting PCC on 1 November 2021. Methods We modeled the prevalence of PCC using reported infections occurring from 1 February 2020 to 30 September 2021, and population-based, household survey data on new activity-limiting symptoms ≥1 month following SARS-CoV-2 infection. From these data sources, we estimated the number and proportion of US adults with activity-limiting PCC on 1 November 2021 as 95% uncertainty intervals, stratified by sex and age. Sensitivity analyses adjusted for underascertainment of infections and uncertainty about symptom duration. Results On 1 November 2021, at least 3.0–5.0 million US adults, or 1.2%–1.9% of the US adult population, were estimated to have activity-limiting PCC of ≥1 month's duration. Population prevalence was higher in females (1.4%–2.2%) than males. The estimated prevalence after adjusting for underascertainment of infections was 1.7%–3.8%. Conclusions Millions of US adults were estimated to have activity-limiting PCC. These estimates can support future efforts to address the impact of PCC on the US population. [ABSTRACT FROM AUTHOR]

Novel low pathogenic avian influenza (LPAI) A(H7N9) virus emerged in February 2013 and, as of March 3, 2015, a total of 602 laboratory-confirmed human infections, including 227 deaths, had been [...]

Background: Global estimates showed an estimate of up to 650,000 seasonal influenza‐associated respiratory deaths annually. However, the mortality rate of seasonal influenza is unknown for most countries in the WHO Eastern Mediterranean Region, including Iran. We aimed to estimate the excess mortality attributable to seasonal influenza in Kerman province, southeast Iran for the influenza seasons 2006/2007–2011/2012. Methods: We applied a Serfling model to the weekly total pneumonia and influenza (PI) mortality rate during winter to define the epidemic periods and to the weekly age‐specific PI, respiratory, circulatory, and all‐cause deaths during non‐epidemic periods to estimate baseline mortality. The excess mortality was calculated as the difference between observed and predicted mortality. Country estimates were obtained by multiplying the estimated annual excess death rates by the populations of Iran. Results: We estimated an annual average excess of 40 PI, 100 respiratory, 94 circulatory, and 306 all‐cause deaths attributable to seasonal influenza in Kerman; corresponding to annual rates of 1.4 (95% confidence interval [CI] 1.1–1.8) PI, 3.6 (95% CI 2.6–4.8) respiratory, 3.4 (95% CI 2.1–5.2) circulatory, and 11.0 (95% CI 7.3–15.6) all‐cause deaths per 100,000 population. Adults ≥75 years accounted for 56% and 53% of all excess respiratory and circulatory deaths, respectively. At country level, we would expect an annual of 1119 PI to 8792 all‐cause deaths attributable to seasonal influenza. Conclusions: Our findings help to define the mortality burden of seasonal influenza, most of which affects adults aged ≥75 years. This study supports influenza prevention and vaccination programs in older adults. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza virus A(H5N1) has been detected among poultry in >60 countries, with sporadic transmission to humans that results in a large number of deaths (1). Of 842 [...]

Background The International Health Regulations outline core requirements to ensure the detection of public health threats of international concern. Assessing the capacity of surveillance systems to detect these threats is crucial for evaluating a country's ability to meet these requirements. Methods and Findings We propose a framework to evaluate the sensitivity and representativeness of hospital-based surveillance and apply it to severe neurological infectious diseases and fatal respiratory infectious diseases in Bangladesh. We identified cases in selected communities within surveillance hospital catchment areas using key informant and house-to-house surveys and ascertained where cases had sought care. We estimated the probability of surveillance detecting different sized outbreaks by distance from the surveillance hospital and compared characteristics of cases identified in the community and cases attending surveillance hospitals. We estimated that surveillance detected 26% (95% CI 18%-33%) of severe neurological disease cases and 18% (95% CI 16%-21%) of fatal respiratory disease cases residing at 10 km distance from a surveillance hospital. Detection probabilities decreased markedly with distance. The probability of detecting small outbreaks (three cases) dropped below 50% at distances greater than 26 km for severe neurological disease and at distances greater than 7 km for fatal respiratory disease. Characteristics of cases attending surveillance hospitals were largely representative of all cases; however, neurological disease cases aged Our estimates of outbreak detection rely on suspected cases that attend a surveillance hospital receiving laboratory confirmation of disease and being reported to the surveillance system. The extent to which this occurs will depend on disease characteristics (e.g., severity and symptom specificity) and surveillance resources. Conclusion We present a new approach to evaluating the sensitivity and representativeness of hospital-based surveillance, making it possible to predict its ability to detect emerging threats., Author(s): Birgit Nikolay 1,2,3, Henrik Salje 1,2,3,4,*, Katharine Sturm-Ramirez 5,6, Eduardo Azziz-Baumgartner 5, Nusrat Homaira 6,7, Makhdum Ahmed 8,9, A. Danielle Iuliano 5, Repon C. Paul 6,10, Mahmudur Rahman 11, [...]

Background: Data on influenza incidence during pregnancy in China are limited. Methods: From October 2015 to September 2018, we conducted active surveillance for acute respiratory illness (ARI) among women during pregnancy. Nurses conducted twice weekly phone and text message follow‐up upon enrollment until delivery to identify new episodes of ARI. Nasal and throat swabs were collected ≤10 days from illness onset to detect influenza. Results: In total, we enrolled 18 724 pregnant women median aged 28 years old, 37% in first trimester, 48% in second trimester, and 15% in third trimester, with seven self‐reported influenza vaccination during pregnancy. In the 18‐week epidemic period during October 2015 to September 2016, influenza incidence was 0.7/100 person‐months (95% CI: 0.5–0.9). In the cumulative 29‐week‐long epidemic during October 2016 to September 2017, influenza incidence was 1.0/100 person‐months (95% CI: 0.8–1.2). In the 11‐week epidemic period during October 2017 to September 2018, influenza incidence was 2.1/100 person‐months (95% CI: 1.9–2.4). Influenza incidence was similar by trimester. More than half of the total influenza illnesses had no elevated temperature and cough. Most influenza‐associated ARIs were mild, and <5.1% required hospitalization. Conclusions: Influenza illness in all trimesters of pregnancy was common. These data may help inform decisions regarding the use of influenza vaccine to prevent influenza during pregnancy. [ABSTRACT FROM AUTHOR]