Flu Vaccination Linked to Lower Heart Attack Risk

Influenza vaccination is associated with significantly lower odds of myocardial infarction (MI), according to a large meta-analysis published late last week in BMC Public Health. 

In the study, researchers led by a team from Zhejiang Chinese Medical University in Hangzhou, China, gathered data from 15 observational studies, including seven cohort studies, seven case-control studies, and one self-controlled case series. Together, the studies involved 23.5 million people. Most participants were older adults, ranging from approximately 57 to 77 years.

In analyzing the pooled data, the researchers found flu vaccination was associated with an 18% reduction (range at the 95% confidence interval, 14% to 22%) in the odds of MI compared with unvaccinated controls. 

Consistent link across studies, patient groups

Subgroup analyses of the data found a consistent link between the flu vaccine and lower odds of heart attack across different types of studies and patient groups. When the team looked at age-stratified results, they found that vaccinated people 70 and older and those 70 and younger had comparably lower risk of heart attack. The same negative association held true for those who had previously had a heart attack compared with those who had not. The flu vaccine was associated with lower odds of MI in both cohort and case-control studies.

Heart attacks tend to be more common during flu season, note the authors, suggesting that viral infections may trigger systemic inflammation and raise the risk of cardiovascular events. 

“Influenza vaccination could potentially reduce the risk of MI by alleviating the systemic inflammation and endothelial dysfunction associated with infection,” the authors write. 

The analysis had some limitations. All included studies were observational and hence cannot establish causality, and flu vaccination was broadly defined, so information on the frequency and timing of vaccination was limited. 

Still, “this meta-analysis indicates that influenza vaccination is associated with lower odds of myocardial infarction,” write the authors, who called for future studies to “clarify the underlying mechanisms and to refine the understanding of this association in contemporary populations.”

Reference: Wu Y, Zhao Y, Liu Z, Zhu A. Influenza vaccination and the risk of myocardial infarction: a meta-epidemiology study. BMC Public Health. 2026. doi: 10.1186/s12889-026-26541-y

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