Effect of Statin Use on Influenza Vaccine Effectiveness

Background: Recent studies suggest that statin use may reduce influenza vaccine effectiveness (VE), but laboratory-confirmed influenza was not assessed.

Methods: Patients ≥45 years old presenting with acute respiratory illness were prospectively enrolled during the 2004-2005 through 2014-2015 influenza seasons. Vaccination and statin use were extracted from electronic records. Respiratory samples were tested for influenza virus.

Results: The analysis included 3285 adults: 1217 statin nonusers (37%), 903 unvaccinated statin nonusers (27%), 847 vaccinated statin users (26%), and 318 unvaccinated statin users (10%). Statin use modified VE and the risk of influenza A(H3N2) virus infection (P = .002) but not 2009 pandemic influenza A(H1N1) virus (A[H1N1]pdm09) or influenza B virus infection (P = .2 and .4, respectively). VE against influenza A(H3N2) was 45% (95% confidence interval [CI], 27%-59%) among statin nonusers and -21% (95% CI, -84% to 20%) among statin users. Vaccinated statin users had significant protection against influenza A(H1N1)pdm09 (VE, 68%; 95% CI, 19%-87%) and influenza B (VE, 48%; 95% CI, 1%-73%). Statin use did not significantly modify VE when stratified by prior season vaccination. In validation analyses, the use of other cardiovascular medications did not modify influenza VE.

Conclusions: Statin use was associated with reduced VE against influenza A(H3N2) but not influenza A(H1N1)pdm09 or influenza B. Further research is needed to assess biologic plausibility and confirm these results.