According to a pair of studies published online Oct. 29 in the Journal of Infectious Diseases, statins – a class of drugs widely utilized by older adults to reduce cholesterol – may have the unintended consequence of reducing immunotherapeutic response to and effectiveness of influenza vaccination.
In a post-hoc analysis (J Infect Dis. 2015 Oct 29. doi: 10.1093/infdis/jiv456), Dr. Steven Black of Cincinnati Children’s Hospital Medical Center and colleagues derived data from an international, multisite, randomized, controlled, influenza vaccine clinical trial population of 6,961 subjects over the age of 65. At 3 weeks post vaccination, the researchers measured the level of antibodies to flu vaccine strains in the blood of both statin and non–statin taking participants. The investigators discovered that hemagglutination-inhibiting geometric mean titers to influenza A (H1NI), A (H3N2), and B strains were 38% (95% confidence interval, 27%-50%), 67% (95% CI, 54%-80%) and 38% (95% CI, 28%-29%) lower, respectively, in the statin therapy arm as compared with the non–statin therapy cohort. The effect was most dramatic in patients on synthetic (as opposed to natural, fermentation-derived) statin treatment regimens.
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“Apparently, statins interfere with the response to influenza vaccine and lower the immune response, and this would seem to also result in a lower effectiveness of influenza vaccines,” Dr. Black and his colleagues wrote. Potential mitigation strategies for statin-induced immunosuppression suggested by the research team include preferential use of high-dose or adjuvanted vaccines.
In addition, a separate retrospective investigation (J Infect Dis. 2015 Oct 29. doi: 10.1093/infdis/jiv457.) tracking 137,488 patients from a Georgia managed care organization database over nine flu seasons (from 2002 to 2011) also generated data implying a connection between statin use and compromised influenza vaccine efficacy and immune response. Dr. Saad Omer of the Emory Vaccine Center at Emory University in Atlanta and his colleagues analyzed the impact of statins on influenza vaccine efficacy against medically attended acute respiratory illness (MAARI). MAARI incidence is routinely employed as an influenza impact marker, although not all MAARI incidence is influenza related.
The Emory University research team found that influenza vaccine effectiveness against MAARI was decreased in statin users, compared with nonusers during periods of local (14.1% vs. 22.9%; mean difference, 11.4%; 95% CI, −1.7%-26.1%) and widespread (12.6% vs. 26.2%; mean difference, 18.4%; 95% CI, 2.9%-36.2%) influenza circulation. “Even after adjustment for several covariates … the observed reduction in influenza vaccine effectiveness among statin users remained statistically significant for periods of widespread influenza circulation with a nonsignificant trend toward reduced vaccine effectiveness during periods of local circulation, as well,” noted Dr. Omer and his coauthors. Said results, wrote the researchers, “have potential implications for clinical guidelines regarding statin use around the time of routine vaccinations.”
Dr. Black is a consultant for Novartis Vaccines, GSK, Takeda Vaccines, Protein Sciences, and the World Health Organization. His coauthors – Dr. Uwe Nicolay, Dr. Giuseppe Del Giudice, and Dr. Rino Rappuoli – are employees of Novartis Vaccines.
Novartis Vaccines funded the post-hoc analysis conducted by Dr. Black and his colleagues, as well as the original clinical trial that developed the data utilized for the analysis. Dr. Omer and his colleagues were funded by Emory University and the National Institute of Allergy and Infectious Diseases and reported no relevant disclosures.