Pregnant women may be particularly vulnerable to developing more severe cases of COVID-19 after SARS-CoV-2 infection, but little is known about their immune response to SARS-CoV- 2 or how it may affect their children. In a study published in JAMA Open Network, a researcher-led group at Massachusetts General Hospital (MGH) provides new insights that could help improve care for these women and their newborns and reinforce the need for pregnant women to be considered in vaccine distribution plans.
The study included 127 pregnant women in their third trimester who were treated at three hospitals in Boston between April 2 and June 13, 2020. Among the 64 women who tested positive for SARS-CoV-2, researchers did not detect a virus in maternal or cord blood (despite being found in the female respiratory system), without the virus in placentas and without evidence of viral transmission to newborns. The researchers suspect that blocking transmission to the fetus could be caused not only by a lack of virus in the mother’s blood, but also by the fact that the main molecules used by SARS-CoV-2 to pass into cells (ACE2 receptor and TMPRSS2 enzyme) frequently or physically located together in the placenta.
Most of the women who tested positive developed antibody responses against SARS-CoV-2 proteins, but maternal transfer to newborns of anti-SARS-CoV-2 antibodies through the placenta was significantly lower than movement of anti-influenza antibodies.
Our finding of maternal-infant transmission of SARS-CoV-2-specific antibodies in third-trimester infections affects maternal vaccine administration. In particular, it appears that pregnant women are a key population to consider in vaccine distribution. It also raises questions about the best time to administer vaccines to best support maternal and neonatal immunity. “
Andrea Edlow, MD, Lead Author, Mother-Fetal Medicine Specialist, MGH and Associate Professor of Obstetrics, Gynecology and Regenerative Biology, Harvard School of Medicine
Edlow notes that transplacental migration of antibodies to the fetus is usually in the third trimester, so it was inconceivable to see less movement of SARS-CoV-2 antibodies compared to those against the flu. “Understanding the mechanisms underlying this ineffective transfer of specific SARS-CoV-2 antibodies after third trimester infection, as well as understanding whether they have the same properties or different at vaccine-generated antibodies than those from actual infection with the virus. for future research, “she says.
Source:
Massachusetts General Hospital
Magazine Reference:
Edlow, AG, et al. (2020) Evaluation of Maternal and Neonatal Viral Loads of SARS-CoV-2, Transplacental Antibody Movement, and Placental Pathology in Pregnancy During the COVID-19 Pandemic. Open JAMA Network. doi.org/10.1001/jamanetworkopen.2020.30455.