Safety of Zostavax™-A cohort study in a managed care organization

► This was an analysis of safety of the zoster vaccine. ► Risk-interval cohort study. ► 29,000 persons who received the zoster vaccine in 2006 and 2007. ► No clear increase in events was observed in the risk period after vaccination compared to later. ► People received zoster vaccine when their health was optimal, which led to confounding.