Health-Related Behaviors and Effectiveness of Trivalent Inactivated versus Live Attenuated Influenza Vaccine in Preventing Influenza-Like Illness among Young Adults

Abstract : Vaccination is the preferred preventive strategy against influenza. Though health behaviors are known to affect immunity and vaccine delivery modes utilize different immune processes, data regarding the preferred influenza vaccine type among adults endorsing specific health-related behaviors are limited. The effectiveness of two currently available influenza vaccines (live, attenuated influenza vaccine [LAIV] and trivalent inactivated influenza vaccine [TIV]) were compared by health-related behavior for prevention of influenza-like illness (ILI) during 2 well-matched influenza seasons (2006/2007, 2008/2009) among US military personnel aged 18-49 years. Relative vaccine effectiveness was compared between those self-reporting and not reporting each health-related behavior (recent smoking history, potential alcohol problem, and exercise level) using Cox proportional hazard modeling adjusted for sociodemographic and military factors, geographic area, and other health behaviors. We studied 28,929 vaccination events and 3936 ILI events over both influenza seasons. Of subjects studied, 27.5% were smokers, 7.7% had a potential alcohol-related problem, 10.5% reported minimal exercise, and 4.4% reported high exercise levels. Overall, the risk of ILI did not significantly differ between LAIV and TIV recipients (hazard ratio, 0.98; 95% confidence interval, 0.90-1.06). In the final adjusted model, the relative effectiveness of the 2 vaccine types did not differ by smoking status (p = 0.10), alcohol status (p = 0.21), or activity level (p = 0.11). TIV and LAIV were similarly effective in preventing ILI among young adults and did not differ by health-related behavior status. Influenza vaccine efforts should continue to focus simply on delivering the vaccine.