A study published in medRxiv this month suggests that antibodies in a mother’s blood can protect newborn babies from acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This finding gives researchers additional insight into how antibodies protect babies against the potential effects of COVID-19.
When babies are born, they have weak immune systems and rely upon maternal antibodies, which they receive through the placenta. However, the types of antibodies transferred can vary if the mother is unwell.
The researchers conducting the study were interested in understanding how COVID-19 affected transplacental transfer of antibodies. The information they have uncovered will help them understand the best strategy for vaccination of expectant mothers when a COVID-19 vaccine becomes available.
The research team looked at serum and cord blood samples from mothers and babies in a Philadelphia hospital between April 9, 2020, and August 8, 2020. The mothers had been regularly tested for COVID-19 or SARS-CoV-2 infection by polymerase chain reaction (PCR) testing of nasopharyngeal specimens.
The research team measured maternal and neonatal IgG and IgM antibodies against the SARS-CoV-2 spike receptor-binding domain (RBD) antigen. From ~1,700 women who had babies delivered, matched paired samples were available for ~1,470 dyads.
The researchers carefully compared the types of antibodies in the mothers and children. They soon discovered that maternal serum antibody levels correlated with cord blood antibodies.
They also looked at the difference in levels of SARS-CoV-2 antibodies between women with severe infections and those with mild or moderate infections. They confirmed an association of higher maternal antibody levels with higher cord antibody levels.
The research suggests that vertical spread of SARS-CoV-2 is unlikely to occur, which means that babies may receive some protection from COVID when they are born. Further research is required to confirm the level of protection conferred.