A recent study evaluated the persistence of maternal anti-S IgG, induced by a COVID-19 vaccine, in infant blood, and compared the persistence of infant anti-S IgG following the mother’s vaccination with natural infection.Women who had received an mRNA COVID-19 vaccine in pregnancy or were infected with COVID at 20 to 32 weeks’ gestation, had enrolled in a prospective study at 2 academic medical centers in Boston, and had enrolled their infants in this follow-up study, were included. Individuals infected before vaccination were excluded from the study. Investigators obtained matched maternal and umbilical cord serum samples at birth. Infant capillary serum samples were obtained 2 months following birth for infants of vaccinated mothers and after 6 months for infants of mothers who were vaccinated and mothers who had been infected with COVID-19. Antibody titers against the virus spike protein were assessed. The study included 77 vaccinated pregnant women and 12 with symptomatic COVID-19 infection in pregnancy. At 2 months, capillary serum samples were obtained from 49 infants of vaccinated mothers, and at 6 months, the samples were obtained from 28 infants of vaccinated mothers and 12 infants of infected mothers.Findings from the study:The titers were significantly higher among vaccinated mothers at delivery with a mean (SD) of 2.03 (0.47) optical density (OD450-570), in comparison with mothers after infection [mean (SD) of 0.65 (0.76) OD450-570] (P