Influenza vaccination attenuates acute myocardial infarction and stroke risk following influenza infection: a register-based, self-controlled case series study, Denmark, 2014 to 2025
Flu shots protect the heart and brain by reducing the severe complications that flu infection triggers in people prone to heart attacks and strokes.
This nationwide Danish SCCS study of >1,200 patients demonstrates that influenza infection dramatically increases short-term risk of first-ever AMI (4.7x) and stroke (2.9x), and that seasonal influenza vaccination substantially reduces this excess cardiovascular risk after breakthrough infection. The findings provide strong real-world evidence supporting influenza vaccination as a cardioprotective intervention, complementing existing vaccine guidance.
What the study was
- Study design
- Nationwide register-based self-controlled case series (SCCS) with conditional Poisson regression
- Population
- Adults ≥40 years with first-ever hospital admission for AMI or stroke within ±365 days of PCR-confirmed influenza, Danish national registries 2014-2025; n=1,221 (AMI 429, stroke 792)
- Sample size
- 1221
- Category
- Prevention
- Maturity
- Validated
- Journal
- Euro Surveillance
Why it surfaced
Rigorous SCCS design using full national Danish registry (11-year span). Quantifies influenza-triggered cardiovascular risk and demonstrates vaccine attenuation. Near-term implementable: directly reinforces current influenza vaccine recommendations with cardiovascular benefit framing. Median age 75 in the cohort — high-priority population for both influenza vaccination and cardiovascular prevention.
A plain-language summary of published research — not medical advice. Talk to a clinician about your own care.