Placental transfer dynamics and durability of maternal COVID-19 vaccine-induced antibodies in infants

Abstract

SUMMARYCompletion of a COVID-19 vaccination series during pregnancy effectively reduces COVID-19 hospitalization among infants less than 6 months of age. Elucidating the dynamics of transplacental transfer of maternal vaccine-induced antibodies, and their persistence in infants at 2, 6, 9 and 12 months, has implications for new vaccine development and timing of vaccine administration in pregnancy to optimize protection of the mother-infant dyad. We evaluated anti-COVID antibody IgG subclass, Fc-receptor binding profile, and activity against wild-type Spike and RBD, and five variants of concern (VOCs) in 153 serum samples from 100 unique infants. Maternal IgG1 and IgG3 responses persisted in 2- and 6-month infants to a greater extent than the other IgG subclasses, with highest persistence of antibodies that bind placental neonatal Fc-receptor as well as FcψR3A. Timing of maternal vaccination and fetal sex were drivers of antibody persistence in infants. Lowest persistence at 2 and 6 months was observed against the Omicron RBD-specific region. Maternal vaccine timing, placental Fc-receptor binding capabilities, antibody subclass, fetal sex, and VOC all impact the persistence of maternal vaccine-induced antibodies in infants up to 12 months.