Insights into pathologic mechanisms occurring during serious adverse events following live zoster vaccination.

An effective live zoster vaccine has been widely used around the world. Although no deaths occurred in the original large clinical trial, we analyzed 10 serious adverse events, including six deaths that have subsequently occurred in four countries. The goal is to define the viral pathogenesis of these unexpected adverse events secondary to a viremia with dissemination of the vaccine virus. We also propose a new hypothesis for acute retinal necrosis that occurs post-immunization.