05.2021
Author Prof. E. Harms, University Department of Pediatrics Münster

Newborns are protected from infection by their innate, immature immune system and by diaplacentally transferred maternal antibodies (Abs). A research team from Philadelphia (USA) looked at a large number of SARS-CoV-2 infection cases that occurred during pregnancy and studied the antibodies to the receptor-binding domain of the SARS-CoV-2 spike protein found in the maternal sera and the neonatal cord blood [1]. The study looked at the sera of 1471 mother/newborn dyads. IgG Abs to SARS-CoV-2 were detected in 83 mothers but only in 72 newborns. However, IgM Abs were not detected in any of the newborns. IgM Abs were detected in 48 mothers with higher titres in those with symptomatic infections.
50 of the 83 mothers were asymptomatic and did not know they were infected. The IgG Ab titre concentration did not correlate with disease progression except in severe cases. Transfer ratios (titre in mother/child) increased with an increase of time between the onset of maternal infection and delivery but were not associated with severity of maternal infection. The transfer ratio in 40 of the 72 seropositive newborns was ≥ 1.