An in-hospital double-dose influenza vaccination strategy's effect on preventing major cardiovascular events (MACE) in patients with previous stroke is still uncertain. This study is a prespecified analysis of the vaccine against influenza to avoid cardiovascular events after the Acute Coronary Syndrome (VIP-ACS) trial. The VIP-ACS trial was a randomized, pragmatic, multicenter, open-label trial with blinded-adjudication endpoints. Adult patients with acute coronary syndrome (ACS) ≤ seven days of hospitalization were randomized to an in-hospital double-dose quadrivalent inactivated influenza vaccine or a standard-dose vaccine at 30 days post-randomization. The primary endpoint was a hierarchical composite of all-cause death, myocardial infarction (MI), stroke, unstable angina, hospitalization for heart failure, urgent coronary revascularization, and hospitalization for respiratory causes, analyzed by the win ratio (WR) method. The secondary endpoint was a hierarchical composite consisting of CV death, MI and stroke (MACE). Patients were followed for 12 months each influenza season. The trial enrolled 1,801 patients (31% female). A total of 67 patients had a history of stroke. There were no significant differences between groups on the primary hierarchical endpoint: 11.4% wins in the double-dose vaccine group vs 12.1% wins in the standard-dose vaccination group (WR:0.97; 95% CI:0.72-1.24; P=0.69) without a history of stroke. However, in-hospital double-dose vaccination favored individuals with previous stroke (WR:2.62; 95% CI:1.10-6.25; P=0.03; 43.9% wins vs. 16.8% wins). Results were consistent for hierarchical MACE (WR:3.01; 95%CI:1.15-7.88; P=0.02; 41.3% wins vs 13.7% wins) in favor of in-hospital double-dose vaccination. After an ACS, in-hospital double-dose influenza vaccination prevents hospitalizations and death compared with standard-dose vaccination at 12 months in individuals with previous strokes.
Fonseca et al. (2025) studied this question.