Antibodies developed against COVID-19 infection during pregnancy can reach the placenta, extending protection to a newborn during its earliest and most vulnerable days of life. But do the antibodies a mother develops after immunization also protect the newborn?

The question holds serious implications, not only because infants may come into contact with unvaccinated individuals, but also because only 40 percent of pregnant people are vaccinated, according to the Centers for Disease Control and Prevention (CDC), and the risk of complications from COVID-19 infection during pregnancy can be dire. “Pregnant people who contract COVID-19 are more likely to require hospitalization, ICU care, and mechanical ventilation,” says maternal–fetal medicine specialist Ashley S. Roman, MD, vice chair for clinical affairs in the Department of Obstetrics and Gynecology at NYU Grossman School of Medicine. “COVID-19 infection can also increase the risk of miscarriage and preterm births.”

Dr. Roman and colleagues at NYU Grossman School of Medicine set out to tackle this big unknown with the first prospective study to evaluate the immune response to mRNA vaccines in pregnancy. In their study, recently published in American Journal of Obstetrics & Gynecology, the researchers found high levels of antibodies unique to the mRNA vaccines in cord blood sampled from 36 pregnant people vaccinated during their first, second, or third trimester who had not contracted COVID-19. “Our data are the first to distinguish between passive immunity from natural infection and immunity from mRNA vaccination,” says primary investigator Jennifer L. Lighter, MD, a hospital epidemiologist at NYU Langone Health. “Not only did all the newborns have antibodies—they had very high levels.”

The protection conferred to newborns was recently confirmed by new data from the CDC, which found that babies born to mothers who received two doses of an mRNA vaccine during pregnancy were 61 percent less likely to be hospitalized with COVID-19 in their first 6 months of life than those born to unvaccinated people.

Building on these findings, NYU Langone’s Vaccine Center is a trial site for a national effort funded by the National Institutes of Health. Called the Multisite Observational Maternal and Infant Study for COVID-19, or MOMI-VAX, the study will evaluate the immune responses generated by COVID-19 vaccines in more than 2,000 pregnant and postpartum patients.

To ensure diversity among participants, NYU Langone has tapped its Family Health Centers at NYU Langone, a large network of clinics providing primary care services to people in underserved areas. “It’s vital to determine how a broad range of patients from different backgrounds respond to the vaccine when administered during pregnancy and how this benefit is conferred to their babies,” adds Dr. Roman.