Incidence of outcomes relevant to vaccine safety monitoring in a US commercially-insured population.

Background: Background incidence rates (IRs) of potential safety outcomes among vaccine eligible individuals can inform assessment of vaccine safety. Vaccine safety surveillance often uses claims databases, but the impact of outcome definitions on background IR estimates is largely unexplored. Using two definitions for each outcome, we estimated background IRs of 32 cardiac, metabolic, allergic, autoimmune, neurologic, hematologic and nephrologic outcomes among individuals eligible to receive pneumococcal vaccination.