The flu shot and cardiovascular Protection: Rethinking inflammation in ischemic heart disease.

Abstract

Influenza infection is a well-established trigger of acute cardiovascular events, particularly myocardial infarction, mediated by systemic inflammation, endothelial dysfunction, and thrombosis. In this review, we examine the evidence supporting influenza vaccination as a preventive strategy in cardiovascular disease. Observational studies and randomized trials consistently show reduced cardiovascular event rates among vaccinated individuals, with the most pronounced benefit seen after myocardial infarction. Emerging data suggest that the effects of vaccination extend beyond infection prevention, involving immunomodulatory effects, including regulatory T cell activity, features of trained innate immunity, and mechanisms promoting resolution of inflammation. Unlike conventional anti-inflammatory therapies, vaccination appears to rebalance immune responses without compromising host defence. We also consider an evolutionary perspective, proposing that historical influenza exposure may have contributed to the genetic architecture of atherosclerosis. Taken together, current evidence positions influenza vaccination as a safe, low-cost, and biologically plausible intervention in the prevention of cardiovascular events. However, important questions remain. Whether revaccination during hospitalization provides added benefit in previously immunized individuals, and the potential of high-dose or next-generation vaccine platforms such as mRNA, warrant further study. Dedicated outcome trials conducted outside the influenza season are especially needed to clarify nonspecific cardiovascular benefits. Cardiologists and other stakeholders share a responsibility to implement existing guidelines with the same commitment given to statins and platelet inhibitors.