Vaccinating women against SARS-CoV-2 in mid to late pregnancy could provide their infants at least some protection against COVID-19 through six months of age, suggests a small study funded by the National Institutes of Health. Compared to infants born to mothers who had COVID-19 during pregnancy, infants born to vaccinated mothers were much more likely to have antibodies against the virus.
The study was conducted by Andrea G. Edlow, M.D., M.Sc., of Massachusetts General Hospital, and colleagues. It appears in JAMA. NIH funding for the study was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Heart, Lung and Blood Institute, and National Institute of Allergy and Infectious Diseases.
COVID-19 vaccination in pregnancy generates antibodies in the mother’s blood against the spike protein, which SARS-CoV-2 uses to infect cells. These anti-spike antibodies can be detected in umbilical cord blood and protect infants from COVID-19. For the current study, researchers sought to determine how long antibodies against the spike protein remained in the infant’s blood. The authors limited their study to individuals vaccinated against SARS-CoV-2 or infected with the virus from 20 to 32 weeks of pregnancy. Previous studies have found that higher levels of antibodies are transferred across the placenta during this time, compared to later in pregnancy.
Researchers collected blood samples of infants born to vaccinated mothers when the infants were two months old. They also collected samples from these infants at six months of age, as well as from six-month-old infants born to mothers who had COVID-19 during pregnancy.
At delivery, vaccinated mothers had higher levels of anti-spike antibodies than mothers who had COVID-19 during pregnancy. At two months of age, 48 out of 49 (98%) of the infants of vaccinated mothers had detectable levels of antibodies. At six months, 16 of 28 (57%) of the infants of vaccinated mothers had detectable levels of antibodies, compared to 1 of 12 (8%) of infants born to mothers who had COVID-19.
The authors noted that infants are more likely to be severely affected by COVID-19 than older children. They added that COVID-19 vaccines currently are not planned for infants younger than six months. Although the study could not determine how much protection that vaccinating mothers confers upon their infants, the authors believe their findings provide incentive for pregnant individuals to get vaccinated.
Shook, LL, et al. Durability of anti-spike antibodies in infants after maternal COVID-19 vaccination or natural infection. JAMA. 2022.