Seasonal Influenza Vaccination Programs in the Americas: A Platform for Sustainable Life-Course Immunization and Its Role for Pandemic Preparedness and Response.

Vaccination is one of the most effective measures to prevent influenza illness and its complications. Since the 1980s, countries and territories in the Americas have progressively implemented influenza vaccination operations in high-risk priority groups-such as older adults, pregnant persons, persons with comorbidities and health workers. In this review, we present the history and progress of the seasonal influenza program in the Americas, how the program contributed to the efficient and timely roll-out of the COVID-19 vaccines during the pandemic, and how the program can be used to promote immunization operations across the life span for existing and future vaccines.

A vicious cycle of frailty and acute lower respiratory infection among community-dwelling adults (≥ 60 years): Findings from a multi-site INSPIRE cohort study, India.

We studied the relationship of frailty and acute lower respiratory infection (ALRI) among a multi-site cohort of community-dwelling older adults aged ≥60 years in India. During January 2019‒January 2020, participants completed the Edmonton Frail Scale (EFS) at baseline and every 3 months at four sites in India, with each participant completing a maximum of four surveys. Participants were categorized as non-frail (0-5 points), vulnerable (6-7 points), and frail (≥8 points) based on EFS score.

Laboratory-Confirmed Influenza Hospitalizations During Pregnancy or the Early Postpartum Period - Suzhou City, Jiangsu Province, China, 2018-2023.

What Is Already Known About This Topic?: Pregnancy is associated with increased risk for severe illness and complications attributable to influenza infection. Information about the incidence of influenza hospitalization among pregnant and early postpartum women in China is limited.

What Is Added By This Report?: Population-based data from a large city in southern China estimated the annual influenza hospitalization rate to be 2.

Laboratory-Confirmed Influenza Hospitalizations During Pregnancy or the Early Postpartum Period - Suzhou City, Jiangsu Province, China, 2018-2023.

Pregnancy is associated with increased risk for severe illness and complications associated with influenza infection. Insufficient knowledge about the risk for influenza among pregnant women and their health care providers in China is an important barrier to increasing influenza vaccination coverage and treating influenza and its complications among pregnant women. Improved influenza incidence estimates might promote wider vaccine acceptance and higher vaccination coverage.

The added value of serologic testing: A comparison of influenza incidence among pregnant persons based on molecular-based surveillance versus serologic testing.

Background: We examined the added value of serologic testing for estimating influenza virus infection incidence based on illness surveillance with molecular testing versus periodic serologic testing.

Methods: Pregnant persons unvaccinated against influenza at <28 weeks gestation were enrolled before the 2017 and 2018 influenza seasons in Peru and Thailand. Blood specimens were collected at enrollment and ≤14 days postpartum for testing by hemagglutination inhibition assay for antibodies against influenza reference viruses.

Randomised immunogenicity trial comparing 2019-2020 recombinant and egg-based influenza vaccines among frequently vaccinated healthcare personnel in Israel.

Objectives: Trivalent inactivated influenza vaccine effectiveness was low in a prospective cohort of healthcare personnel (HCP) in Israel from 2016 to 2019. We conducted a randomised immunogenicity trial of quadrivalent recombinant influenza vaccine (RIV4) and standard-dose inactivated influenza vaccine (IIV4) among frequently and infrequently vaccinated previous cohort participants.

Methods: From October 2019 to January 2020, we enrolled and randomly allocated HCP from two Israeli hospitals to receive IIV4 or RIV4.

Healthcare personnel acceptance and recommendations for influenza vaccine in twelve low- and middle-income countries: A pooled analysis from 2018 to 2020.

Background: Although healthcare personnel (HCP) are targeted for influenza vaccination they typically underutilize vaccines especially in low- and middle-income countries. We explored knowledge, attitudes, and practices of HCP about seasonal influenza vaccines (SIV) to identify factors associated with and modifiable barriers to SIV uptake.

Methods: We pooled individual-level data from cross-sectional surveys about SIV conducted among health workers in 12 low- and middle- income countries during 2018-2020 (i.

Incidence of laboratory-confirmed influenza and RSV and associated presenteeism and absenteeism among healthcare personnel, Israel, influenza seasons 2016 to 2019.

BackgroundHealthcare personnel (HCP) are at high risk for respiratory infections through occupational exposure to respiratory viruses.AimWe used data from a prospective influenza vaccine effectiveness study in HCP to quantify the incidence of acute respiratory infections (ARI) and their associated presenteeism and absenteeism.MethodsAt the start and end of each season, HCP at two Israeli hospitals provided serum to screen for antibodies to influenza virus using the haemagglutination inhibition assay.

Cost-effectiveness of seasonal influenza vaccination in WHO-defined high-risk populations in Bangladesh.

Background: Bangladesh carries a substantial health and economic burden of seasonal influenza, particularly among the World Health Organization (WHO)-defined high-risk populations. We implemented a modelling study to determine the cost-effectiveness of influenza vaccination in each of five high-risk groups (pregnant women, children under five years of age, adults with underlying health conditions, older adults (≥60 years), and healthcare personnel) to inform policy decisions on risk group prioritisation for influenza vaccination in Bangladesh.

Methods: We implemented a Markov decision-analytic model to estimate the impact of influenza vaccination for each target risk group.

Post-discharge mortality among patients hospitalised with severe acute respiratory infection, Bangladesh, 2012-2019: a prospective observational study.

Background: Enhancing outcomes post-hospitalisation requires an understanding of predictive factors for adverse events. This study aimed to estimate post-discharge mortality rates among patients with severe acute respiratory infection (SARI) in Bangladesh, identify associated factors, and document reported causes of death.

Methods: From January 2012 to December 2019, we conducted follow-up calls to patients or their families 30 days after discharge to assess the status of patients with SARI.

Incidence of Hospitalization due to Influenza-Associated Severe Acute Respiratory Infection During 2010-2019 in Bangladesh.

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.

Do pregnant persons want influenza vaccines? Knowledge, attitudes, perceptions, and practices toward influenza vaccines in 8 low- and middle-income countries.

Background: While vaccination is the most effective way to prevent influenza infection and adverse outcomes, and despite WHO recommendations to vaccinate pregnant persons, access to seasonal influenza vaccines remains low. We explored knowledge, attitudes, and practices of pregnant persons about seasonal influenza vaccines to inform actions to improve vaccine uptake among this priority population.

Methods: We pooled individual-level data from cross-sectional surveys assessing pregnant persons' attitudes toward seasonal influenza vaccines in eight low- and middle-income countries during 2018-2019.

Adverse outcomes in patients hospitalized with pneumonia at age 60 or more: A prospective multi-centric hospital-based study in India.

Background: Limited data exists regarding risk factors for adverse outcomes in older adults hospitalized with Community-Acquired Pneumonia (CAP) in low- and middle-income countries such as India. This multisite study aimed to assess outcomes and associated risk factors among adults aged ≥60 years hospitalized with pneumonia.

Methods: Between December 2018 and March 2020, we enrolled ≥60-year-old adults admitted within 48 hours for CAP treatment across 16 public and private facilities in four sites.

Estimating averted illnesses from influenza vaccination for children and pregnant women - El Salvador, Panama, and Peru, 2011-2018.

Background: Estimating the burden of disease averted by vaccination can assist policymakers to implement, adjust, and communicate the value of vaccination programs. Demonstrating the use of a newly available modeling tool, we estimated the burden of influenza illnesses averted by seasonal influenza vaccination in El Salvador, Panama, and Peru during 2011-2018 among two influenza vaccine target populations: children aged 6-23 months and pregnant women.

Methods: We derived model inputs, including incidence, vaccine coverage, vaccine effectiveness, and multipliers from publicly available country-level influenza surveillance data and cohort studies.

Association between SARS-CoV-2 infection and select symptoms and conditions 31 to 150 days after testing among children and adults.

Background: An increasing number of studies have described new and persistent symptoms and conditions as potential post-acute sequelae of SARS-CoV-2 infection (PASC). However, it remains unclear whether certain symptoms or conditions occur more frequently among persons with SARS-CoV-2 infection compared with those never infected with SARS-CoV-2. We compared the occurrence of specific COVID-associated symptoms and conditions as potential PASC 31- to 150-day following a SARS-CoV-2 test among adults and children with positive and negative test results.

Costs and cost-effectiveness of influenza illness and vaccination in low- and middle-income countries: A systematic review from 2012 to 2022.

Background: Historically, lack of data on cost-effectiveness of influenza vaccination has been identified as a barrier to vaccine use in low- and middle-income countries. We conducted a systematic review of economic evaluations describing (1) costs of influenza illness; (2) costs of influenza vaccination programs; and (3) vaccination cost-effectiveness from low- and middle-income countries to assess if gaps persist that could hinder global implementation of influenza vaccination programs.

Methods And Findings: We performed a systematic search in Medline, Embase, Cochrane Library, CINAHL, and Scopus in January 2022 and October 2023 using a combination of the following key words: "influenza" AND "cost" OR "economic.

Etiology of Acute Lower Respiratory Illness Hospitalizations Among Infants in 4 Countries.

Background: Recent studies explored which pathogens drive the global burden of pneumonia hospitalizations among young children. However, the etiology of broader acute lower respiratory tract infections (ALRIs) remains unclear.

Methods: Using a multicountry study (Albania, Jordan, Nicaragua, and the Philippines) of hospitalized infants and non-ill community controls between 2015 and 2017, we assessed the prevalence and severity of viral infections and coinfections.

Effectiveness of COVID-19 vaccines against hospitalisation in Latin America during three pandemic waves, 2021-2022: a test-negative case-control design.

Background: Vaccine effectiveness (VE) is essential to monitor the performance of vaccines and generate strategic information to guide decision making. We pooled data from six Latin American countries to estimate the effectiveness of COVID-19 vaccines in preventing laboratory-confirmed SARS-CoV-2 hospitalisation during three different pandemic waves from February 2021 to September 2022.

Methods: We used a test-negative case-control design in hospitalised adults in Chile, Costa Rica, Ecuador, Guatemala, Paraguay, and Uruguay.

Strengthening influenza surveillance capacity in the Eastern Mediterranean Region: Nearly two decades of direct support from the United States Centers for Disease Control and Prevention.

Since 2004, the US 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. The substantial growth of influenza surveillance capacities in the region demonstrates a commitment by governments to strengthen national programs and contribute to global surveillance. The full value of surveillance data is in its use to guide local public health decisions.