Effects of annual influenza vaccination on mortality in patients with heart failure.

The objective was to evaluate the effect of influenza vaccine on all-cause mortality in a cohort of patients with heart failure followed up in primary care centres of the Community of Madrid, Spain, during the period 2006-10. Results of the Cox proportional-hazard model were adjusted for age and sex and, after 1:1 nearest neighbour matching, for propensity score. The analysis was further stratified by season. Having received annual influenza vaccine was associated with a decreased risk of death during the influenza season (hazard ratio = 0.59, 95% CI = 0.41-0.84), but no protective effect was observed before or after the influenza season.