ArticleVaccine: X2019
Influenza vaccine effectiveness against hospitalizations in children and older adults-Data from South America, 2013-2017. A test negative design.
Article in Vaccine: X, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 16 papers, 2 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
16 citing papers in PubMed, 2 syntheses or guidelines pooled it, 26 citations in OpenAlex.
- Impact of COVID-19 pandemic on influenza vaccination rates among healthcare workers and the general population in Saudi Arabia: A meta-analysis.Human vaccines & immunotherapeutics · 2025Pooled it
- Comparison of 2 Doses vs 1 Dose in the First Season Children Are Vaccinated Against Influenza: A Systematic Review and Meta-Analysis.JAMA network open · 2025Pooled it
- Validity of influenza vaccine effectiveness calculations using a test-negative design in Thailand.American journal of epidemiology · 2026Article
- Annual Estimation of Seasonal Influenza Burden in 6 South American Countries: A Retrospective Analysis of SARInet Surveillance Data to Inform Policies.The Journal of infectious diseases · 2025Article
- Effectiveness of 2023 southern hemisphere influenza vaccines against severe influenza-associated illness: pooled estimates from eight countries using the test-negative design.The Lancet. Global health · 2025Article
- Interim Effectiveness Estimates of 2024 Southern Hemisphere Influenza Vaccines in Preventing Influenza-Associated Hospitalization - REVELAC-i Network, Five South American Countries, March-July 2024.MMWR. Morbidity and mortality weekly report · 2024Article
- Timing of seasonal influenza epidemics for 25 countries in Africa during 2010-19: a retrospective analysis.The Lancet. Global health · 2023Article
- Effectiveness of Maternal Influenza Vaccination in Peru PRIME Cohort.Open forum infectious diseases · 2023Article
- Severity of influenza illness by seasonal influenza vaccination status among hospitalised patients in four South American countries, 2013-19: a surveillance-based cohort study.The Lancet. Infectious diseases · 2023Article
- Influenza incidence and vaccine effectiveness during the Southern Hemisphere Influenza season-Chile, 2022.American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons · 2022Article
- Influenza Incidence and Vaccine Effectiveness During the Southern Hemisphere Influenza Season - Chile, 2022.MMWR. Morbidity and mortality weekly report · 2022Article
- Incidence of respiratory virus illness and hospitalizations in a Panama and El Salvador birth cohort, 2014-2018.Lancet regional health. Americas · 2022Article
- Mitigating co-circulation of seasonal influenza and COVID-19 pandemic in the presence of vaccination: A mathematical modeling approach.Frontiers in public health · 2022Article
- Incidence and seasonality of respiratory viruses among medically attended children with acute respiratory infections in an Ecuador birth cohort, 2011-2014.Influenza and other respiratory viruses · 2022Article
- Article
- Safety, Immunogenicity, Efficacy and Effectiveness of Inactivated Influenza Vaccines in Healthy Pregnant Women and Children Under 5 Years: An Evidence-Based Clinical Review.Frontiers in immunology · 2021Review
Corrections and comments
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Authors and funding
15 authors at 8 institutions in 6 countries.
Funding
Abstract
backgroundIn 2013, the Pan American Health Organization established a multi-site, multi-country network to evaluate influenza vaccine effectiveness (VE). We pooled data from five consecutive seasons in five countries to conduct an analysis of southern hemisphere VE against laboratory-confirmed influenza hospitalizations in young children and older adults.
methodsWe used a test-negative design to estimate VE against laboratory-confirmed influenza in hospitalized young children (aged 6─24 months) and older adults (aged ≥60 years) in Argentina, Brazil, Chile, Colombia, and Paraguay. Following country-specific influenza surveillance protocol, hospitalized persons with severe acute respiratory infections (SARI) at 48 sentinel hospitals (March 2013-December 2017) were tested for influenza virus infection by rRT-PCR. VE was estimated for young children and older adults using logistic random effects models accounting for cluster (country), adjusting for sex, age (months for children, and age-in-year categories for adults), calendar year, country, preexisting conditions, month of illness onset and prior vaccination as an effect modifier for the analysis in adults.
resultsWe included 8426 SARI cases (2389 children and 6037 adults) in the VE analyses. Among young children, VE against SARI hospitalization associated with any influenza virus was 43% (95%CI: 33%, 51%) for children who received two doses, but was 20% (95%CI: -16%, 45%) and not statistically significant for those who received one dose in a given season. Among older adults, overall VE against SARI hospitalization associated with any influenza virus was 41% (95%CI: 28%, 52%), 45% (95%CI: 34%, 53%) against A(H3N2), 40% (95%CI: 18%, 56%) against A(H1N1)pdm09, and 20% (95%CI: -40%, 54%) against influenza B viruses.
conclusionsOur results suggest that over the five-year study period, influenza vaccination programs in five South American countries prevented more than one-third of laboratory confirmed influenza-associated hospitalizations in young children receiving the recommended two doses and vaccinated older adults.
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