They said it couldn’t happen, but then they hadn’t studied it either: Now, COVID vaccine researchers know that the mRNA spreads to the breast milk of lactating women.

“Our findings demonstrate that the COVID-19 vaccine mRNA is not confined to the injection site but spreads systemically and is packaged into breast milk (BM) extracellular vesicles (EV),” study authors wrote in The Lancet. While the EVs didn’t express the SARS-COV-2 spike protein, researchers said the mRNA “spreads systemically and is packaged into BM EVs.”

Even so, they still believe the jab is safe, although mothers should have “a dialogue” with their health care providers on the risks and benefits of breastfeeding in the first two days after taking the shot, they said.

Addressing the study’s findings in an upcoming edition, the Journal of American Medical Association (JAMA) urges mothers to be cautious about breastfeeding babies under 6 months old for 48 hours after taking the shot.

“The potential interference of COVID-19 vaccine mRNA with the immune response to multiple routine vaccines given to infants during the first six months of age needs to be considered,” JAMA reviewers said. “It is critical that lactating individuals be included in future vaccination trials to better evaluate the effect of mRNA vaccines on lactation outcomes.”

SOURCES:

The Lancet September 19, 2023

JAMA September 26, 2023