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Breastfeeding mothers who have been vaccinated against COVID-19 likely pass their antibodies on to their babies, a new study has found.

The research, out of Washington University School of Medicine in St. Louis., believe the nursing mothers pass on antibodies through their breast milk, giving their children a “huge boost” against COVID-19.

“Our study showed a huge boost in antibodies against the COVID-19 virus in breast milk starting two weeks after the first shot, and this response was sustained for the course of our study, which was almost three months long,” first author Jeannie Kelly, assistant professor of obstetrics and gynecology, said in a press release. “The antibodies levels were still high at the end of our study, so the protection likely extends even longer.”

The small study, involving just five mothers, provides “some of the first peer-reviewed evidence that breastfeeding confers a long-lasting immune response” in the nursing children of vaccinated mothers, the study said.

Though other recent studies have confirmed that COVID-19 vaccines can pass their benefits onto infants through breast milk, according to the Washington University researchers, this is the first study to track specific levels of antibodies in breast milk over an extended period of time.

The babies in the study ranged in age from one month to 24 months. To identify the immune response in the breast milk, researchers monitored levels of specific immunoglobulins, which the body uses to fight infection in babies.

The study confirms that breast milk contains elevated levels of certain antibodies immediately after vaccination, with the antibodies “reaching immune-significant levels” around 14 to 20 days after the first vaccination.

“Our study is limited by a small number of participants, but the findings provide encouraging news about the potential immune benefit to breast-feeding infants after vaccination,” said study senior author Misty Good, MD, an assistant professor of pediatrics, in a statement.

The study was published March 30 in the American Journal of Obstetrics and Gynecology.