Influenza vaccination is associated with a reduced risk of myocardial infarction

The pooled analysis found that those vaccinated against influenza were 18% less likely to have a myocardial infarction compared with those not vaccinated (95% confidence interval, 14% to 22%). This association persisted across different types of studies and different patient groups. When analyzed separately by age, the risk reduction was observed in both people under 70 and those older. A similar trend was observed in patients who had already had a heart attack, compared with those who had not previously had one. The association between vaccination and a lower risk of heart attack has been found in both cohort studies and case-control studies.

The authors note that heart attacks occur more frequently during the influenza season, which may indicate a role for viral infections in triggering systemic inflammation and increasing cardiovascular risk.

However, the study has limitations: all included studies were observational, which means they do not allow us to talk about a direct cause-and-effect relationship. In addition, information on the frequency and timing of vaccination was incomplete.

However, the authors emphasize that the findings suggest an association between influenza vaccination and a lower risk of myocardial infarction and call for further research to clarify the mechanisms behind this effect.