SARS‐CoV‐2 IgG “heritage” in newborn: a credit of maternal natural infection

Description of transplacental passage of specific SARS-CoV-2 IgG from mothers who contracted natural infection to their newborns. Retrospective cohort analysis including pregnant women diagnosed with SARS-CoV-2 and their newborns both tested for SARS-CoV-2 specific IgG and IgM with antibody titration at delivery. Nasopharyngeal swab were taken from both mothers and neonates, and tested for SARS-CoV-2 using polymerase chain reaction (PCR). IgM and IgG were analyzed in maternal and neonatal serum of 143 mother-infant dyads. 86% of women with a positive SARS-CoV-2 PCR >14 days before delivery developed specific IgG and 84% of their infants showed transplacental passage of IgG. Pregnant women infected with SARS-CoV-2 achieve antibody seroconversion following the kinetics described in the general population, and transplacental transfer of IgG specific antibodies occurs. No conclusion can be drawn on passive immunity efficacy or duration.