What are the effects of annual influenza vaccination on winter mortality in elderly people with chronic heart disease?
A study conducted by de Diego et al. (2008) found that annual influenza vaccination was associated with a decreased risk of winter mortality in elderly people with chronic heart disease. The authors compared two groups of elderly people with chronic heart disease, one of which received an annual influenza vaccination and one of which did not. After analyzing the data, they found that the group that received the annual influenza vaccination had a 39% lower risk of winter mortality than the group that did not receive the vaccination. Additionally, several other studies (Couch et al., 2007; Keitel et al., 2006) have also demonstrated the safety and immunogenicity of high dosage trivalent influenza vaccines in elderly individuals.  