Quantitative Analysis of Vertical Transmission of Maternal SARS-CoV-2 Antibodies to Neonates and Young Infants Following Immunization During Pregnancy.

Serum antibody levels to SARS-CoV-2 in infants born to mothers who had received 2 doses of the BNT2b2 vaccine during pregnancy correlated positively with increasing gestational age at vaccination (P < .01) and negatively with increasing time from vaccination (P < .01), with a significant drop in infants aged >60 days (P = .045).