Models of Phase 1 vaccine trials: optimization of trial design to minimize risks of multiple serious adverse events.

A mathematical model of Phase 1 vaccine trial design was used to investigate strategies for minimizing the number of serious adverse events (SAEs) that could be encountered in the first Phase 1 trials of new vaccine formulations. For a relatively standard dose escalation trial with three dose groups each with 10 subjects, an optimal balanced between risk of more than one serious adverse event and trial design is achieved by splitting each dose group into two subgroups of three and seven. Based on the modeling, for a two vaccination, dose-escalating Phase 1 trial, a design where all subjects receive the first vaccination before any subject receives a second vaccination generally carries a lower risk of multiple serious adverse events than other designs.