Association between immunogenicity and reactogenicity: a post hoc analysis of two Phase 3 studies with the adjuvanted recombinant zoster vaccine.

A recurrent question is whether transient reactions to vaccines translate into better immune responses. Using clinical data from two large Phase 3 studies of the recombinant zoster vaccine, we observed a small but statistically significant association between the intensity of a frequent side-effect (pain) after vaccination and immune responses to vaccination. However, despite the statistical correlation, the impact on the immune response is so small, and the immune response in individuals without pain already sufficient, that pain cannot be a surrogate marker for an appropriate immune response. Reactogenicity cannot be used to predict immunity after vaccination.