Influenza Vaccination Is Not Associated with a Reduction in the Risk of Recurrent Coronary Events

Abstract

Acute respiratory infections, including influenza, have been suggested as possible precipitants of acute cardiac events. To evaluate whether influenza vaccination prevents recurrent coronary events, the authors conducted a population-based inception cohort study of 1,378 Group Health Cooperative enrollees who survived a first myocardial infarction in 1992 through 1996. Recurrent coronary events, influenza vaccinations, and other covariates were identified by chart review and from administrative data systems. A Cox proportional hazards model was used to evaluate the association of receipt of each year's influenza vaccine with subsequent risk of recurrent myocardial infarction and death from atherosclerotic cardiovascular disease. A total of 127 recurrent coronary events were identified during the median 2.3-year follow-up period. Influenza vaccination was not associated with risk of recurrent coronary events during the corresponding period of November through October (adjusted hazard ratio (HR) = 1.18, 95% confidence interval (CI): 0.79, 1.75) or during the corresponding periods of expected influenza activity (November through April) (HR = 1.06, 95% CI: 0.63, 1.78) or inactivity (May through October) (HR = 1.34, 95% CI: 0.76, 2.36). These results suggest that the benefit of influenza vaccine for older adults does not extend to protection against recurrent coronary events.

Influenza Vaccination and Risk of Incident Myocardial Infarction

“…27 In contrast, an observational study by Jackson and coworkers conducted among the same population as in the current study using follow-up data collected after incident MI suggests that influenza vaccination is not protective against recurrent coronary events. 16 Our findings may differ from those of other studies for several reasons. First, the outcome of interest in our study, incident MI, differed from the outcomes of interest in these other studies.…”

“…15 However, results of one study suggest that influenza vaccination is not protective against recurrent coronary events. 16 To further assess the association between influenza vaccination and risk of incident MI in persons 65 years of age and older, we conducted a population-based case-control study of patients enrolled in a health maintenance organization.…”

Inflammation-related effects of adjuvant influenza A vaccination on platelet activation and cardiac autonomic function

“…However, the ability of the influenza A vaccination to reduce the risk of acute coronary events remains debated, as discordant results have been reported [31][32][33]. The increased platelet activation observed after vaccination in our study might transiently increase the risk of thrombosis in high-risk patients.…”

Influenza and Cardiovascular Disease

“…Another casecontrol study reported a 50% risk reduction (OR 0.50, 95% CI 0.26 to 0.94, Pϭ0.033) in stroke risk in subjects vaccinated during the year of the study and a 48% (OR 0.42, 95% CI 0.21 to 0.81, Pϭ0.009) risk reduction in those vaccinated during the last 5 years. 19 In a recent study by Jackson et al 20 on a cohort of survivors from a first MI, influenza vaccination was not associated with reduced risk of recurrent coronary events during the corresponding period of November through October (adjusted hazard ratio 1.18, 95% CI 0.79 to 1.75). The study by Jackson et al 20 was conducted in a cohort of health maintenance organization patients who may have received better health care than patients in other studies.…”

“…19 In a recent study by Jackson et al 20 on a cohort of survivors from a first MI, influenza vaccination was not associated with reduced risk of recurrent coronary events during the corresponding period of November through October (adjusted hazard ratio 1.18, 95% CI 0.79 to 1.75). The study by Jackson et al 20 was conducted in a cohort of health maintenance organization patients who may have received better health care than patients in other studies. In this study, 74% of subjects received at least 1 influenza vaccine during the follow-up period (43% to 66% per year), which is much higher than the national average ratio (Ϸ30%).…”