COVID-19 vaccination before or during pregnancy results in high, sustained maternal neutralizing activity to SARS-CoV-2 wild-type and Delta/Omicron variants of concern, particularly following a booster dose or infection.

Objectives: To investigate multi-dose and timings of COVID-19 vaccines in preventing antenatal infection.

Design: Prospective observational study investigating primary vaccinations, boosters, antenatal COVID-19 infections, neutralizing antibody (Nab) durability, and cross-reactivity to Delta and Omicron variants of concern (VOCs).

Results: Ninety-eight patients completed primary vaccination prepregnancy (29.