Newborns are born with SARS-CoV-2 antibodies transferred in utero from their mothers

A University of Pennsylvania-Children's Hospital of Philadelphia research team with which I collaborate just published a paper in JAMA Pediatric today demonstrating that SARS-CoV-2 antibodies in the blood passed from mothers to babies through the placenta, so newborns tended to have similar antibody levels as their mothers.

Only the IgG antibodies were transferred, not the IgM, but the IgG antibodies are the ones that are longer-lasting and thought to be most pivotal in future immune protection.

These data were collected in the fall before vaccination started, so these antibodies came from natural infections, either known or unknown to the women. It is not clear whether vaccine-induced antibodies are similarly passed on to the fetus and newborn from the mother, but future studies will investigate this question.