SynthesisThe Lancet. Respiratory medicine2023
Does repeated influenza vaccination attenuate effectiveness? A systematic review and meta-analysis.
Synthesis in The Lancet. Respiratory medicine, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 71 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
71 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Systematic review of influenza vaccine effectiveness against laboratory-confirmed influenza among older adults living in aged care facilities.Human vaccines & immunotherapeutics · 2023Pooled it
- Comparison of the immunogenicity of adjuvanted and conventional egg-based quadrivalent influenza vaccines among healthcare personnel in Lima, Peru: A randomized controlled trial.International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases · 2026Trial
- Enhanced Influenza Vaccines Extend A(H3N2) Antibody Reactivity in Older Adults but Prior Vaccination Effects Persist.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2025Trial
- Preliminary Findings From the Dynamics of the Immune Responses to Repeat Influenza Vaccination Exposures (DRIVE I) Study: A Randomized Controlled Trial.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2024Trial
- Redirecting antibody responses from egg-adapted epitopes following repeat vaccination with recombinant or cell culture-based versus egg-based influenza vaccines.Nature communications · 2024Trial
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- Article
- The Dual Role of Preexisting Immunity in Influenza: Protective Recall Versus Constraint of Novel Responses.Immunological reviews · 2026Review
- Repeated influenza vaccination results in blunting rather than back-boosting of antibody responses against A(H3N2) antigens.Research square · 2026Article
- Influenza vaccine effectiveness against outpatient acute respiratory illness with laboratory-confirmed influenza, United States, 2024-25 season.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2026Article
- Repeat Influenza Vaccination Effects in 2021/22 and 2022/23 in a Community-Based Cohort in Hong Kong.The Journal of infectious diseases · 2026Article
- Influenza Vaccination Effectiveness Against Influenza-Associated Hospitalization in Children and the Effects of Repeated Vaccination.The Journal of infectious diseases · 2026Article
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- Article
- Article
- Effectiveness of Seasonal Influenza Vaccination Against Medically Attended Influenza in People With Chronic Respiratory Diseases: A Multicenter, Test-Negative, Case-control Study.Open forum infectious diseases · 2026Article
- Influenza vaccine effectiveness against outpatient acute respiratory illness with laboratory-confirmed influenza, United States, 2024-25 season.medRxiv : the preprint server for health sciences · 2026Article
- Epitope-spanning antigenic variation reprograms immunodominance and broadens immunity in sequential influenza vaccination.Nature communications · 2026Article
- Article
- Low effectiveness of influenza vaccines vis-à-vis mechanism of protection by vaccines - potential causes and recommendations to improve control of influenza.Frontiers in immunology · 2026Review
11 more citing papers are in PubMed but not listed here.
Corrections and comments
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Authors and funding
5 authors.
Funding
Abstract
backgroundInfluenza vaccines require annual readministration; however, several reports have suggested that repeated vaccination might attenuate the vaccine's effectiveness. We aimed to estimate the reduction in vaccine effectiveness associated with repeated influenza vaccination.
methodsIn this systematic review and meta-analysis, we searched MEDLINE, EMBASE, and CINAHL Complete databases for articles published from Jan 1, 2016, to June 13, 2022, and Web of Science for studies published from database inception to June 13, 2022. For studies published before Jan 1, 2016, we consulted published systematic reviews. Two reviewers (EJ-G and EJR) independently screened, extracted data using a data collection form, assessed studies' risk of bias using the Risk Of Bias In Non-Randomized Studies of Interventions (ROBINS-I) and evaluated the weight of evidence by Grading of Recommendations Assessment, Development, and Evaluation (GRADE). We included observational studies and randomised controlled trials that reported vaccine effectiveness against influenza A(H1N1)pdm09, influenza A(H3N2), or influenza B using four vaccination groups: current season; previous season; current and previous seasons; and neither season (reference). For each study, we calculated the absolute difference in vaccine effectiveness (ΔVE) for current season only and previous season only versus current and previous season vaccination to estimate attenuation associated with repeated vaccination. Pooled vaccine effectiveness and ∆VE were calculated by season, age group, and overall. This study is registered with PROSPERO, CRD42021260242.
findingsWe identified 4979 publications, selected 681 for full review, and included 83 in the systematic review and 41 in meta-analyses. ΔVE for vaccination in both seasons compared with the current season was -9% (95% CI -16 to -1, I
interpretationOur estimates suggest that, although vaccination in the previous year attenuates vaccine effectiveness, vaccination in two consecutive years provides better protection than does no vaccination. The estimated effects of vaccination in the previous year are concerning and warrant additional investigation, but are not consistent or severe enough to support an alternative vaccination regimen at this time.
fundingWHO and the US National Institutes of Health.
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Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.