Influenza Vaccination as Cardiovascular Prevention in Adults with Heart Disease

Seasonal influenza is not only a respiratory infection but also a clinically relevant trigger of acute cardiovascular events. In adults with established cardiovascular disease, particularly older adults and patients with recent acute coronary syndrome or heart failure, influenza vaccination should be considered a low-risk, evidence-supported component of cardiovascular prevention rather than solely protection against respiratory disease. The evidence addresses three related but distinct questions: influenza infection as a cardiovascular trigger; influenza vaccination versus placebo or no vaccination; and enhanced or high-dose vaccination versus standard-dose vaccination. Randomized trials and meta-analyses support reductions in major adverse cardiovascular events, cardiovascular mortality, and all-cause mortality in higher-risk secondary-prevention populations, with particularly persuasive evidence after myocardial infarction. Recent pragmatic active-comparator trials of high-dose inactivated influenza vaccine, including DANFLU-2 and GALFLU, and the individual-level pooled FLUNITY-HD analysis provide incremental evidence in adults aged 65 years or older, strongest for hospitalization for influenza or pneumonia, cardiorespiratory hospitalization, and heart failure hospitalization. The current priority is implementation: screening, offering, documenting, and communicating vaccination across hospitalization, outpatient cardiology, cardiac rehabilitation, heart failure pathways, primary care, pharmacies, and long-term care. Influenza vaccination should complement, not replace, established guideline-directed cardiovascular therapies.