COVID vaccine antibodies found in breast milk of vaccinated mothers

A new study has emerged that brings promising news for some of our most vulnerable in the COVID-19 pandemic: babies.

Mounting evidence has found that COVID-vaccine antibodies are present in vaccinated mothers’ breast milk, which means vaccinated, breastfeeding mothers can potentially provide passive immunity against the virus to their infants.

Pregnant and breastfeeding women and those who have been recently pregnant are strongly urged by the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics (AAP) and numerous other physician associations across the country to get vaccinated as soon as possible.

And given the fact that we’re seeing more and more pediatric cases making up a larger share of weekly COVID cases (22.4%, according to the most recent AAP data), here’s yet another reason why vaccination is a good idea.

COVID-19 antibodies can pass through breastmilk.

The most recent study was published in the journal Breastfeeding Medicine by a team of researchers out of the University of Florida, who analyzed breast milk samples of 21 breastfeeding healthcare workers who received the first Pfizer and Moderna vaccines between December 2020 and March 2021. Researchers took samples of the mothers’ breast milk and blood before vaccination, after the first dose and again after the second dose.

They found impressively high levels of SARS-CoV-2 immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies secreted in the women’s breast milk, especially after the second shot, adding to the promising evidence showing similar results.

Current research is very encouraging.

The study was small, but the results are very promising—and in line with how we expect vaccines to work. The vaccinated mothers produced antibodies at levels high enough that they were then secreted through their breast milk. Pregnant women are also urged to get vaccinated against the flu and whooping cough in pregnancy so as to confer benefits—antibodies against the illnesses—to their babies once born. While more long-term and larger-scope studies are definitely warranted, the results of this research make a good case for adding a COVID-19 vaccination to that list going forward.

And though it’s still unclear how much COVID-19 immunity is conferred to breastfed children from maternal vaccination, the results are heartening.

“There is still so much we are learning about breast milk and all its benefits, and that’s what makes this research so fascinating—not just for us scientists but for non-scientists, too,” says Lauren Stafford, an author of the study, in ScienceDaily.

Passive immunity is not the same as being vaccinated, but it’s still helpful.

While passive immunity does not equate to active immunity, it does offer some protection—given what we know about how antibodies in breast milk can protect children from other viruses.

Maternal vaccination can provide a layer of protection for breastfed babies and young children, who may otherwise be unprotected. And though COVID-19 cases in children tend to be mild, children under 2 years of age are especially vulnerable and more likely to be hospitalized with the disease.

“Think of breast milk as a toolbox full of all the different tools that help prepare the infant for life. Vaccination adds another tool to the toolbox, one that has the potential to be especially good at preventing COVID-19 illness,” says Josef Neu, M.D., a co-author of the study and a professor in the UF College of Medicine’s department of pediatrics, division of neonatology, in ScienceDaily. “The results of our study strongly suggest that vaccines can help protect both mom and baby, another compelling reason for pregnant or lactating women to get vaccinated.”

Breastfeeding mothers who have been infected with COVID-19 can pass some antibodies built up in their own immune systems to their infants, but experts believe these aren’t as long-lasting as those created as a result of vaccination, which elicits a more standardized response.

“These levels [seen in the study] are also higher than those observed after natural infection with the virus,” says Vivian Valcarce, M.D., a resident in the UF College of Medicine’s department of pediatrics, division of neonatology, and an author of the study, in ScienceDaily.

Of course, other precautions against the virus should still be taken into account by parents too, especially if you have a child under 2, such as social distancing and frequent hand-washing and vaccinating all family members who are eligible. All of these are crucial steps in helping to reduce the virus’ spread.

Sources:

Kim, L., Whitaker, M., O’Halloran, A., Kambhampati, A., Chai, S. J., Reingold, A., Armistead, I., Kawasaki, B., Meek, J., Yousey-Hindes, K., Anderson, E. J., Openo, K. P., Weigel, A., Ryan, P., Monroe, M. L., Fox, K., Kim, S., Lynfield, R., Bye, E., Shrum Davis, S., … COVID-NET Surveillance Team (2020). Hospitalization Rates and Characteristics of Children Aged <18 Years Hospitalized with Laboratory-Confirmed COVID-19 – COVID-NET, 14 States, March 1-July 25, 2020. MMWR. Morbidity and mortality weekly report, 69(32), 1081–1088. https://doi.org/10.15585/mmwr.mm6932e3

Perl SH, Uzan-Yulzari A, Klainer H, Asiskovich L, Youngster M, Rinott E, Youngster I. SARS-CoV-2–Specific Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women. JAMA. 2021 May 18;325(19):2013-4. doi:10.1001/jama.2021.5782

Valcarce V, Stafford LS, Neu J, Cacho N, Parker L, Mueller M, Burchfield DJ, Li N, Larkin J. Detection of SARS-CoV-2 specific IgA in the human milk of COVID-19 vaccinated, lactating health care workers. Breastfeeding Medicine. 2021. https://doi.org/10.1089/bfm.2021.0122