Maternal and neonatal anti-SARS-CoV-2 IgG antibody levels: a comparative study of infected and/or vaccinated pregnant women

Introduction This study aimed to measure anti-SARS-CoV-2 IgG antibody levels in pregnant women with COVID-19 infection and/or vaccination and their newborns, and to assess antibody levels in newborns relative to maternal levels. A total of 204 participants were included: Group 1 (n = 52 mothers with infection and/or vaccination, including 18 with hybrid immunity) and Group 2 (their 52 newborns), compared with Group 3/4 controls (50 unexposed mother-newborn pairs).Results Group 3/4 controls were seronegative. Mean IgG was 1084.8 IU/ml in mothers (Group 1) and 1036.9 IU/ml in newborns (Group 2), with the highest levels in the hybrid immunity subgroup (maternal: 1680.5; neonatal: 1506.9 IU/ml). Natural infection alone did not significantly affect maternal antibody levels (p = 0.810), while vaccination (p = 0.032) and hybrid immunity (p = 0.006) were significantly correlated with higher maternal IgG.Commentary Both COVID-19 infection and vaccination during pregnancy lead to significant maternal antibody production and substantial antibody levels in newborns. However, vaccination and particularly hybrid immunity serve as the primary drivers for achieving the highest antibody titers, emphasizing the strategic importance of maternal vaccination for neonatal protection.