Women who receive an mRNA-based COVID-19 vaccination or booster during pregnancy can provide their infants with strong protection against symptomatic COVID-19 infection for at least six months after birth, according to a new study by the U.S. National Institutes of Health (NIH).

An earlier study revealed that when pregnant volunteers received both doses of an mRNA COVID-19 vaccine, antibodies induced by the vaccine could be found in their newborns' cord blood. This suggested that the infants likely had some protection against COVID-19 when they were still too young to receive a vaccine, the NIH said in a release on Wednesday.

However, researchers did not know how long these antibody levels would last or how well the infants would actually be protected.

In this study, NIH researchers analyzed data from 475 infants at nine sites across the U.S. The infants were evaluated in at least one follow-up visit during their first six months after birth.

Based on blood samples from the infants, the researchers found that newborns with high antibody levels at birth also had greater protection from COVID-19 infection during their first six months.

These findings, which were published in Pediatrics, reinforce the importance of receiving both a COVID-19 vaccine and booster during pregnancy to ensure that infants are born with robust protection that lasts until they are old enough to be vaccinated, said the NIH.