- Influenza infection acutely increases cardiovascular risk: The risk of first myocardial infarction or stroke was ~3.5-fold higher in the first week after infection, peaking within 3 days.
- Myocardial infarction risk rises more than stroke risk: The relative increase was greater for myocardial infarction (IRR 4.7) than for stroke (IRR 2.9).
- Vaccination is associated with lower postinfection risk: Prior influenza vaccination was linked to substantially lower excess cardiovascular risk (IRR 2.4 vs 4.7), suggesting attenuation of risk after breakthrough infection.
- Risk is short-lived but clinically meaningful: Elevated risk was concentrated in the first 7 days and returned to baseline within about 2–4 weeks, highlighting a narrow window of vulnerability.
- Findings support vaccination in at-risk patients: Results suggest influenza vaccination may provide cardiovascular benefit beyond infection prevention, particularly in patients at risk for myocardial infarction or stroke.
Flu Vaccination Linked to Lower Heart, Stroke Risk After Infection
Conexiant
April 7, 2026
