A meta-analysis on the efficacy of influenza vaccine in reducing cardiovascular mortality and myocardial infarction in patients with cardiovascular disease

Type of funding sources: None.

Influenza infection has been linked to adverse cardiovascular events in coronary artery disease (CAD) patients. Despite the compelling link between influenza vaccine’s protective potential in observational studies, the RCTs that supports it are small.

This meta-analysis sought to determine if the current collective data support reduction of cardiovascular death, and myocardial infarction among patients with cardiovascular disease.

RCTs and observational studies in Cochrane, Pubmed and Google Scholar that fulfilled the inclusion and exclusion criteria were subjected to fixed effect analysis as to the primary and secondary outcomes.

Analyses were stratified by study design into RCTs and observational studies. A total of 8 studies (n=150111) including 4 RCTs (n=3921) and 4 observational studies (n= 146190) were identified. At a median follow-up of 19.7 months, influenza vaccine was associated with lower risk of cardiovascular death (RR 0.73, 95% CI [0.72, 0.74]) with a p= <0.00001 compared with control. Influenza vaccine was not associated with statistically significant reduction in myocardial infarction ( RR0.82, 95% Ci, [0.66, 1.02]) with a p= 0.06 compared with control.

Influenza vaccine reduced the risk of cardiovascular death in patients with cardiovascular disease. There was no significance in the secondary endpoint of myocardial infarction in the vaccine and placebo arm. The strategies that support cardiovascular risk mitigation, including the cardioprotective potential of influenza vaccine should be a central therapeutic priority especially in the low to moderate income countries.