Influenza vaccination and the risk of myocardial infarction: a meta-epidemiology study
Abstract
BACKGROUND: The association between influenza vaccination and the risk of myocardial infarction (MI) remains incompletely characterized, particularly in real-world populations. We conducted a meta-epidemiological study to evaluate the association between influenza vaccination and incident MI using evidence from observational studies. METHODS: We systematically searched PubMed, Embase, and the Cochrane Library from inception to July 16, 2025 for cohort and case-control studies examining influenza vaccination and MI. Adjusted effect estimates were extracted and pooled as odds ratios (ORs) using random-effects models. Study quality was assessed with the Newcastle–Ottawa Scale. Subgroup analyses and meta-regression were performed to explore potential sources of heterogeneity, and publication bias was assessed using funnel plots and Egger’s test. RESULTS: Fifteen studies (seven cohort studies, seven case-control studies, and one self-controlled case-series) involving 23,484,167 individuals were included. Influenza vaccination was associated with lower odds of MI compared with no vaccination (OR = 0.82; 95% CI: 0.78–0.86; I² = 65.6%; P < 0.001). The direction of association was consistent across study designs, age categories, and MI history. Subgroup estimates were broadly comparable, although several analyses were based on a limited number of studies and should be interpreted with caution. Meta-regression did not identify study design, age, prior MI, or follow-up duration as…
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