COVID antibodies may pass on to newborns.
One of the many big questions scientists are trying to untangle is whether people who get COVID-19 during pregnancy will pass on some natural immunity to their newborns.
Recent studies have hinted that they might. And new findings, published Friday in the journal JAMA Pediatrics, provide another piece of the puzzle, offering more evidence that COVID-19 antibodies can cross the placenta.
“What we have found is fairly consistent with what we have learned from studies of other viruses,” said Scott Hensley, an associate professor of microbiology at the Perelman School of Medicine at the University of Pennsylvania and one of the senior authors of the study.
Additionally, he added, the study suggests that women are not only transferring antibodies to their fetuses, but also transferring more antibodies to their babies if they are infected earlier in their pregnancies. This might have implications for when women should be vaccinated against COVID-19, Hensley said, adding that vaccinating women earlier in pregnancy might offer more protective benefits, “but studies actually analyzing vaccination among pregnant women need to be completed.”
In the study, researchers from Pennsylvania tested more than 1,500 women who gave birth at Pennsylvania Hospital in Philadelphia between April and August 2020. Of those, 83 women were found to have COVID-19 antibodies — and after they gave birth, 72 of those babies tested positive for COVID-19 antibodies via their cord blood, regardless of whether their mothers had symptoms.
According to Dr. Karen Puopolo, an associate professor of pediatrics at Penn and one of the senior authors of the study, about half of those babies had antibody levels that were as high or higher than those found in their mother’s
blood, and in about a quarter of the cases, the antibody levels in the cord blood was 1.5 to 2 times higher than the mother’s concentrations.
“That’s fairly efficient,” Puopolo said.
The researchers also observed that the longer the time period between the start of a pregnant woman’s COVID-19 infection and her delivery, the more antibodies were transferred, a finding that has been noted elsewhere.
The antibodies that crossed the placenta were immunoglobulin G, or IgG, antibodies, the type that are made days after getting infected and are thought to offer long-term protection against the coronavirus.
None of the babies in this study were found to have immunoglobulin M, or IgM, antibodies, which are typically only detected soon after an infection, suggesting that the babies hadn’t been infected with the coronavirus.
Experts don’t yet know if the amount of antibodies that passed on to the babies was enough to prevent newborns from getting COVID-19.
And because only a few of the babies in the study were born prematurely, the researchers can’t say whether babies who are born early might miss out on those protective antibodies.
The study authors also noted that because their results were from just one facility, the findings would need to be further replicated.