ArticleAmerican journal of infection control2021
Impact of the influenza vaccine on COVID-19 infection rates and severity.
Article in American journal of infection control, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 112 papers, 4 of them syntheses that pooled it.
What it found
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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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
112 citing papers in PubMed, 4 syntheses or guidelines pooled it, 175 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
- The effect of influenza vaccine in reducing the severity of clinical outcomes in patients with COVID-19: a systematic review and meta-analysis.Scientific reports · 2022Pooled it
- The Association Between Previous Influenza Vaccination and COVID-19 Infection Risk and Severity: A Systematic Review and Meta-analysis.American journal of preventive medicine · 2022Pooled it
- Modeling the impact of adherence to U.S. isolation and masking guidance on SARS-CoV-2 transmission in office workplaces in 2021-2022.Epidemics · 2026Article
- Association between COVID-19 booster vaccination and influenza mortality: a nationwide retrospective cohort study using the SIVEP-Gripe database in Brazil.Immunologic research · 2026Article
- Modeling the impact of adherence to U.S. isolation and masking guidance on SARS-CoV-2 transmission in office workplaces in 2021-2022.medRxiv : the preprint server for health sciences · 2026Article
- Immune Priming and the Risk of COVID-19, Influenza, and Other Acute Respiratory Infections: Insights From an N3C Cohort.Influenza and other respiratory viruses · 2026Article
- Investigating the relationship between influenza vaccination and COVID-19 infection: a cohort study in Tehran.BMC infectious diseases · 2025Article
- Article
- Association between influenza vaccine effectiveness and chronic diseases among older adults with dementia.Scientific reports · 2025Article
- Biometric Strategies to Improve Vaccine Immunogenicity and Effectiveness.Biomimetics (Basel, Switzerland) · 2025Review
- Modelling the interplay between responsive individual vaccination decisions and the spread of SARS-CoV-2.Epidemics · 2025Article
- Relationship between influenza-related experience and current vaccination outcome.BMC public health · 2025Article
- Pulmonary lymphoid tissue induced after SARS-CoV-2 infection in rhesus macaques.Frontiers in immunology · 2025Article
- Clinical status and cytokine profiles in patients with asthma or chronic obstructive pulmonary disease vaccinated against influenza.PloS one · 2025Article
- Progress in combination vaccines and the co-administration of influenza virus and SARS-CoV-2 vaccines.Frontiers in immunology · 2025Review
- Association between combination COVID-19-influenza vaccination and long COVID in middle-aged and older Europeans: A cross-sectional study.Human vaccines & immunotherapeutics · 2024Article
- Relative effectiveness of a heterologous booster dose with adenovirus type 5 vectored COVID-19 vaccine versus three doses of inactivated COVID-19 vaccine in adults during a nationwide outbreak of omicron predominance, in China: a retrospective, individually matched cohort-control study.Emerging microbes & infections · 2024Article
- Factors associated with outcome in a national cohort of rhinovirus hospitalized patients in Brazil in 2022.Scientific reports · 2024Article
52 more citing papers are in PubMed but not listed here.
Corrections and comments
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Authors and funding
5 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundWith a unique influenza season occurring in the midst of a pandemic, there is interest in assessing the role of the influenza vaccine in COVID-19 susceptibility and severity.
methodsIn this retrospective cohort study, patients receiving a laboratory test for COVID-19 were identified. The primary outcome was comparison of positive COVID-19 testing in those who received the influenza vaccine versus those who did not. Secondary end points in patients testing positive for COVID-19 included mortality, need for hospitalization, length of stay, need for intensive care, and mechanical ventilation.
resultsA total of 27,201 patients received laboratory testing for COVID-19. The odds of testing positive for COVID-19 was reduced in patients who received an influenza vaccine compared to those who did not (odds ratio 0.76, 95% CI 0.68-0.86; P < .001). Vaccinated patients testing positive for COVID-19 were less likely to require hospitalization (odds ratio, 0.58, 95% CI 0.46-0.73; P < .001), or mechanical ventilation (odds ratio, 0.45, 95% CI 0.27-0.78; P = .004) and had a shorter hospital length of stay (risk ratio, 0.76, 95% CI 0.65-0.89; P < .001).
conclusionInfluenza vaccination is associated with decreased positive COVID-19 testing and improved clinical outcomes and should be promoted to reduce the burden of COVID-19.
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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.