Pregnant women can be especially vulnerable to developing more severe cases of Covid-19 after SARS-CoV-2 infection, but little is known about their immune response or how it can affect their offspring. A study published in ‘JAMA Network Open’ notes that infected pregnant women do not transmit viruses to newborns but they have fewer antibodies than expected.
A group led by researchers from Massachusetts General Hospital (MGH) provides new insights with their study that could help improve the care of these women and their newborns and emphasizes the need for pregnant women to be considered in the implementation plans of vaccinations
The study included 127 pregnant women in their third trimester who received care at three Boston hospitals between April 2 and June 13, 2020. Among the 64 women who tested positive for SARS-CoV-2, the researchers did not detect virus in the maternal or umbilical cord blood (despite detection in the female respiratory system), there are no signs of the virus in the placentas and there is no evidence of viral transmission to newborns.
Researchers suspect that transmission to the fetus may be blocked not only due to the lack of virus in the mother’s blood, but also because the main molecules that SARS-CoV-2 uses to enter cells (ACE2 receptor and TMPRSS2 enzyme ) often are not physically located together in the placenta.
Most of the women who tested positive developed antibody responses to SARS-CoV-2 proteins, but transfer from mother to newborn of anti-SARS-CoV-2 antibodies across the placenta was significantly less than transfer anti-flu antibodies.
“Our finding of a compromised mother-to-baby transfer of SARS-CoV-2 specific antibodies in third trimester infections have implications for maternal vaccine administration -Explain-. Specifically, it highlights that pregnant women are a key population to consider in vaccine launches. ”
“It also raises questions about the optimal timing of vaccine administration to better support maternal and neonatal immunity,” adds lead author Andrea Edlow, a maternal-fetal medicine specialist at MGH and an assistant professor of obstetrics, gynecology and reproductive biology at the Harvard Medical School.
Edlow notes that the transplacental transfer of antibodies to the fetus is typically highest in the third trimester, so it was unexpected to see a significantly reduced transfer of antibodies against SARS-CoV-2 compared to flu.
“Understand the mechanisms underlying this ineffective transfer of SARS-CoV-2-specific antibodies after third-trimester infection, as well as understand whether the antibodies generated by the vaccine have the same or different properties from actual infection with the viruses will be fundamental directions for future research “, he concludes.
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