COVID vaccines and breastfeeding: what the data say
To that end, the World Health Organization recommends that mothers continue to breastfeed after vaccination. In addition, the CDC and the UK Joint Committee on Vaccination and Immunisation issued statements shortly after the first vaccines were authorized in both countries. These noted that no safety concerns had been identified from the available data, so lactating people could choose to be vaccinated.
“It’s sort of a backwards way of recommending it,” argues Christina Chambers, a paediatrician at the University of California, San Diego, and the Rady Children’s Hospital. “The foundation is that there’s no reason to avoid it, which is a dilemma.”
So Gaw and her colleagues ran a safety check. In a small study3, her team looked at breast milk samples from six participants up to two days after they received the Pfizer–BioNTech or Moderna vaccine, and found no trace of the mRNA in either case. (The group is now scouring a larger number of milk samples for different components of the vaccine, and expanding their study to include all the available COVID-19 vaccines in the United States.)
There is one type of particle that scientists are eager to see in breast milk following a vaccine: COVID-19 antibodies.
Researchers have long known that newborn babies don’t effectively produce antibodies against harmful bacteria and viruses; and it can take three to six months for this kind of protection to kick in. To help in those early days, a mother’s breast milk overflows with antibodies capable of staving off potential threats.
“It’s specifically designed by the mother, and by Mother Nature, to provide the child with the child’s first vaccine,” says Hedvig Nordeng at the University of Oslo, who specializes in medication use and safety in pregnancy and lactation. “Breast milk by itself is more than nutrition, breast milk is medicine.”