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Clinical Summary

Influenza Vaccine Offers Cardiovascular Benefits in Individuals at Varying Cardiovascular Risk


  • Influenza vaccine was associated with a lower risk of cardiovascular (CV) events, irrespective of the underlying CV risk.

Why This Matters

  • Findings suggest that improved vaccine uptake may help reduce the risk of first acute CV events in people who are already eligible to receive the seasonal influenza vaccine.

Study Design

  • The observational study included 193,900 participants (age 40-84 years) with a first acute CV event using linked data from the UK Clinical Practice Research Datalink, Hospital Episode Statistics Admitted Patient Care, and Office for National Statistics (2009-2019).
  • Primary outcome: any CV event (myocardial infarction, unstable angina, acute left ventricular heart failure, stroke, transient ischaemic attack, or acute limb ischaemia).
  • Secondary outcomes: individual CV events except acute limb ischaemia.
  • Funding: Wellcome Trust.

Key Results

  • Overall, 105,539 participants had hypertension and 172,050 had a QRISK2 score of ≥10%.
  • There was a significant reduction in the risk of acute CV events in the 15-28 days post-vaccination (incidence ratio [IR] 0.72; 95% CI 0.70 to 0.74).
  • These effects tapered but remained significant in the 91-120 days post-vaccination (IR 0.84; 95% CI 0.82 to 0.85).
  • A significant reduction was obseved in individual CV events, but the reduction was more significant in myocardial infarction than other CV events (15-28 days: IR 0.60; 95% CI 0.57 to 0.64).
  • The risk of acute CV events significantly reduced post-vaccination among individuals across all age groups and with raised and lower CV risk.


  • Observational design.
  • Risk of confounding.