Estimated Burden of Influenza and Direct and Indirect Benefits of Influenza Vaccination

In this analytical model study, influenza vaccination provided substantial benefit in reducing infections to both the vaccinated and unvaccinated portions of the population. Even when both vaccine effectiveness and vaccine uptake were low, vaccination showed marked reductions in disease burden for transmission levels characteristic of seasonal influenza. However, when the level of transmission was very high, even a highly effective vaccine did not protect unvaccinated individuals. These findings underscore the importance of vaccination in disease prevention and control and show that indirect benefits are limited in high transmission situations.