Influenza Vaccination and Risk of Incident Myocardial Infarction

Abstract

Background: Several studies suggest that influenza vaccination may be associated with a decreased risk of acute cardiovascular events. We examined the association between influenza vaccination and risk of incident myocardial infarction (MI) in persons at least 65 years of age in a population-based case-control study.Methods: Case subjects were members of Group Health Cooperative (GHC), a health maintenance organization, with incident MI during 1992-1998. Control subjects were GHC members without a history of MI who were frequency matched to case subjects by age, sex, calendar year, and presence of treated hypertension. The medical records of 750 case subjects with MI and 1735 controls were reviewed.Results: Receipt of influenza vaccine was not associated with risk of incident MI during the months of November through March (odds ratio [OR]: 0.97, 95% confidence interval [CI]: 0.75-1.27) or April through September (OR: 0.97, 95% CI 0.75-1.26).Conclusions: This study does not provide evidence supporting an association of influenza vaccination and reduction in risk of myocardial infarction.

Influenza vaccination and cardiovascular risk in patients with recent TIA and stroke

“…A recent case-control study found no association between stroke and influenza vaccination, 8 and negative results have also been found in the prevention of myocardial infarction. [24][25][26] There is also the possibility that, because of publication bias, other negative studies have not been published. However, above all, observational studies may be biased and this is particularly true for influenza vaccination studies.…”

Influenza vaccination, pneumococcal vaccination and risk of acute myocardial infarction: matched case-control study

“…10,18 Studies with no evidence of benefit had low power, poor case ascertainment, misclassification of vaccination status and lack of investigator blinding. [19][20][21] The additional benefit of early within-season influenza vaccination (i.e., during the period from September to mid-November) compared with late vaccination (i.e., after mid-November) has been suggested by findings of previous research, 22 but is not part of current recommendations for influenza vaccination. 23 Given that influenza vaccination is likely to be effective only against circulating strains of influenza virus, our findings are strengthened by the biological plausibility of a within-season or within-year effect of influenza vaccination in preventing influenza-related acute myocardial infarction.…”

Influenza Vaccination for Secondary Prevention of Cardiovascular Events: A Systematic Review

“…Furthermore, the study was likely underpowered because of the small proportion of patients with a history of CVD. The 2 matched case-control studies 26,27 were heterogeneous with regard to results: one showed a benefit with influenza vaccine, whereas the other was neutral. However, both of these studies were limited by differences in baseline characteristics that were not adjusted for in the analyses.…”

“…[26][27][28] All 3 studies were deemed to be of low or very low quality according to the GRADE criteria.…”

“…Heffelfinger and others 27 performed a case-control study in a health maintenance organization in Seattle, Washington. Included were 750 cases (women or hypertensive men) aged 65-79 years with fatal or nonfatal myocardial infarction who were matched by sex, age category, calendar year, and presence of pharmacologically treated hypertension to 1735 controls from a stratified random sample.…”