COVID-19 vaccination during pregnancy brings baby long-term protection

Babies whose moms were vaccinated during pregnancy against COVID-19 have long-lasting antibody protection, a new study finds.

"Many interested parties from parents to pediatricians want to know how long maternal antibodies persist in infants after vaccination, and now we can provide some answers," said co-senior study author Dr. Andrea Edlow. She is a specialist in maternal-fetal medicine at Massachusetts General Hospital (MGH), in Boston.

For the study, Edlow and her team compared babies born to women who had received two doses of an mRNA vaccine with those born to unvaccinated mothers who were infected with COVID-19 at 20 to 32 weeks of pregnancy. That's the period when the transfer of antibodies from mother to fetus is at its highest.

At delivery, antibody levels were higher in vaccinated mothers and their umbilical cord blood than in the unvaccinated, infected mothers.

At two months of age, 48 of 49 infants (98%) born to vaccinated moms had detectable levels of the protective Immunoglobulin G (IgG), the most common antibody found in blood.

At six months of age, 16 of 28 infants (57%) born to vaccinated mothers still had detectable IgG levels, compared with one of 12 (8%) born to unvaccinated infected mothers, according to the report published online recently in the Journal of the American Medical Association.

While Edlow said it's still unclear how high antibody levels need to be to completely protect an infant from COVID-19, anti-spike IgG levels protect from serious illness.

"The durability of the antibody response here shows vaccination not only provides lasting protection for mothers but also antibodies that persist in a majority of infants to at least 6 months of age," she said in a hospital news release.

The researchers hope these and other recent findings will provide incentive for pregnant women to get vaccinated, especially with the emergence of new variants of concern like Omicron.

Co-senior study author Galit Alter, of the Ragon Institute of MGH, Massachusetts Institute of Technology and Harvard, noted that pregnant women are at extremely high risk for serious complications from COVID-19.

"And given the lag in development of COVID-19 vaccines for infants, these data should motivate mothers to get vaccinated and even boosted during pregnancy to empower their babies' defenses against COVID," Alter said.

More information

For more about vaccination during pregnancy, visit the March of Dimes.