The Phase 2 portion of the study will include approximately 350 pregnant women randomized 1:1 to receive BNT162b2 or placebo (saline) at 27 to 34 weeks gestation. IRC review of safety data through 7 days after the second dose for all Phase 2 participants will be completed before participants in the Phase 3 portion can be enrolled.

The Phase 3 portion of this study will assess the safety, tolerability, and immunogenicity of BNT162b2 among pregnant women enrolled at 24 to 34 weeks gestation.

Maternal participants who originally received a placebo will receive BNT162b2 at defined time points as part of the study.