title: Influenza vaccination, pneumococcal vaccination and risk of acute myocardial infarction: matched case-control study.
abstract: BACKGROUND
  Previous studies have shown an association between acute myocardial infarction and preceding respiratory infection. Contradictory evidence exists on the influence of influenza vaccination and pneumococcal vaccination in preventing cardiovascular disease. We aimed to investigate the possible association of influenza vaccination and pneumococcal vaccination with acute myocardial infarction.
  
  
  METHODS
  We used a matched case-control design with data from the United Kingdom General Practice Research Database. Cases were patients who were at least 40 years of age at diagnosis of first acute myocardial infarction recorded from Nov.1, 2001, to May 31, 2007, and were matched for sex, general practice, age and calendar time (i.e., month corresponding to index date of acute myocardial infarction), with up to four controls each. Data were analyzed using conditional logistic regression, adjusted for vaccination target groups, cardiovascular risk factors, treatment medications and attendances at a general practice.
  
  
  RESULTS
  We included 78 706 patients, of whom 16 012 were cases and 62 694 were matched controls. Influenza vaccination had been received in the previous year by 8472 cases (52.9%) and 32 081 controls (51.2%) and was associated with a 19% reduction in the rate of acute myocardial infarction (adjusted odds ratio [OR] 0.81, 95% confidence interval [CI] 0.77-0.85). Early seasonal influenza vaccination was associated with a lower rate of acute myocardial infarction (adjusted OR 0.79, 95% CI 0.75-0.83) than vaccination after mid-November (adjusted OR 0.88, 95% CI 0.79-0.97). Pneumococcal vaccination was not associated with a reduction in the rate of acute myocardial infarction (adjusted OR 0.96, 95% CI 0.91-1.02).
  
  
  CONCLUSIONS
  Influenza vaccination but not pneumococcal vaccination is associated with a reduced rate of first acute myocardial infarction. This association and the potential benefit of early seasonal vaccination need to be considered in future experimental studies.
authors.forename: A Niroshan
authors.initials: AN
authors.lastname: Siriwardena
authors.forename: Stella M
authors.initials: SM
authors.lastname: Gwini
authors.forename: Carol A C
authors.initials: CA
authors.lastname: Coupland
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000517:prevention & control*; D016017:Odds Ratio; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D007252:Influenza Vaccines; D022242:Pneumococcal Vaccines