SynthesisAmerican journal of preventive medicine2022
The Association Between Previous Influenza Vaccination and COVID-19 Infection Risk and Severity: A Systematic Review and Meta-analysis.
Synthesis in American journal of preventive medicine, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 35 papers, 2 of them syntheses 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
35 citing papers in PubMed, 2 syntheses or guidelines pooled it, 51 citations in OpenAlex.
- Vaccination against influenza viruses reduces infection, not hospitalization or death, from respiratory COVID-19: A systematic review and meta-analysis.Journal of medical virology · 2024Pooled it
- Association between influenza vaccination and SARS-CoV-2 infection and its outcomes: systematic review and meta-analysis.Chinese medical journal · 2022Pooled it
- Association between COVID-19 booster vaccination and influenza mortality: a nationwide retrospective cohort study using the SIVEP-Gripe database in Brazil.Immunologic research · 2026Article
- Vaccination Coverage Against Coronavirus Disease 2019 (COVID-19) in Brazil's Indigenous Population.Journal of medical virology · 2026Article
- Respiratory syncytial virus infection induces heterologous protection against SARS-CoV-2 through γδ T cell-mediated trained immunity and the activation of SARS-CoV-2-reactive mucosal T cells.Journal of virology · 2026Article
- Potential Non-Specific Benefits of Seasonal Influenza Vaccination: Evidence, Knowledge Gaps, and Future Directions.Vaccines · 2026Review
- The role of virus in nasal inflammation.European journal of medical research · 2025Review
- Clinical status and cytokine profiles in patients with asthma or chronic obstructive pulmonary disease vaccinated against influenza.PloS one · 2025Article
- Changes in the Epidemiological Features of Influenza After the COVID-19 Pandemic in China, the United States, and Australia: Updated Surveillance Data for Influenza Activity.Interactive journal of medical research · 2024Article
- Article
- Influenza Vaccination Mediates SARS-CoV-2 Spike Protein Peptide-Induced Inflammatory Response via Modification of Histone Acetylation.Vaccines · 2024Article
- Flu vaccine administration in the period before SARS-CoV-2 infection and its outcomes: An umbrella review.Preventive medicine reports · 2024Review
- Influenza vaccination as a prognostic factor of humoral IgA responses to SARS-CoV-2 infection.Central-European journal of immunology · 2024Article
- Seroprevalence of SARS-CoV-2 antibodies among healthcare workers in Dutch hospitals after the 2020 first wave: a multicentre cross-sectional study with prospective follow-up.Antimicrobial resistance and infection control · 2023Article
- A Cross-Sectional Survey of Knowledge, Attitude, and Practices Regarding Influenza Vaccination Among Jordanians Aged 18-64 Years with Chronic Diseases.Turkish journal of pharmaceutical sciences · 2023Article
- Lower risk for COVID-19 hospitalization among patients in the United States with past vaccinations for herpes zoster and tetanus, diphtheria and pertussis.Preventive medicine reports · 2023Article
- Experimental Infection of Pigs with a Traditional or a Variant Porcine Respiratory Coronavirus (PRCV) Strain and Impact on Subsequent Influenza A Infection.Pathogens (Basel, Switzerland) · 2023Article
- Lower frequency of SARS-CoV-2-associated severe respiratory infections among adults vaccinated against the 2021/22 season influenza.Respiratory medicine and research · 2023Article
- Effects of pneumococcal conjugate vaccines on reducing the risk of respiratory disease associated with coronavirus infection.Pneumonia (Nathan Qld.) · 2023Review
- Article
Corrections and comments
- Erratum issued
Authors and funding
10 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
introductionThe association between influenza vaccination and COVID-19 remains controversial. This meta-analysis aimed to investigate whether influenza vaccination reduces the susceptibility and severity of SARS-CoV-2 infection.
methodsA systematic literature search of PubMed, Web of Science, the Cochrane Library, Embase, China National Knowledge Infrastructure, SinoMed, Wanfang Data Knowledge Service Platform, and China Science and Technology Journal VIP Database was conducted from database inception to August 2021. The pooled RR with 95% CI was used to estimate the effect of influenza vaccination on COVID-19. The I
resultsA total of 23 published articles with 1,037,445 participants were identified. This meta-analysis showed that influenza vaccination was associated with reduced risk of COVID-19 infection (RR=0.83, 95% CI=0.76, 0.90) and hospitalization (RR=0.71, 95% CI=0.59, 0.84), although not significantly associated with intensive care unit admission and death (risk of intensive care unit admission: RR=0.93, 95% CI=0.64, 1.36; risk of death: RR=0.83, 95% CI=0.68, 1.01). Further analysis suggested that the tetravalent influenza vaccine may be associated with a reduced risk of COVID-19 infection (RR=0.74, 95% CI=0.65, 0.84). DISCUSSION: The results suggest that influenza vaccination is associated with reduced susceptibility to or disease severity of COVID-19 and that influenza vaccination may reduce the risk of COVID-19 and improve clinical outcomes.
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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.