TORONTO — Although the current COVID-19 vaccines have not been approved for infants, it turns out there may be another way babies can get antibodies in their system: through the breast milk of mothers who have been vaccinated themselves.
Several recent studies have shown that antibodies can be passed from mothers to their infants through breastfeeding.
Previous studies looked at mothers who were infected with COVID-19 themselves, but emerging data has also looked at whether vaccinated mothers may be able to pass along antibodies.
One small study, published at the end of March in the American Journal of Obstetrics and Gynecology, tracked five women for a period of several months in order to measure how long antibodies might be present in breast milk after vaccination.
By looking at samples of breast milk taken at different stages, they found that there were still protective antibodies in the women’s breast milk 80 days after they had been vaccinated with the Pfizer vaccine.
“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,” Jeannie Kelly, first author and assistant professor of obstetrics and gynecology at the Washington University School of Medicine, said in a press release Tuesday. “The antibodies levels were still high at the end of our study, so the protection likely extends even longer.”
Although it’s impossible to know definitively if the antibodies would prevent an infant from contracting COVID-19, the level of antibodies in the breast milk was found to reach “immune-sufficient levels” a little over two weeks after the first shot, the release stated.
“So, getting vaccinated while breastfeeding not only protects mom, but also could protect the baby, too, and for months,” Kelly said.
Misty Good, an assistant professor of pediatrics at Washington University and senior author of the study, said in the release that although they are limited by the small number of participants, the research still provides “encouraging news.”
“Our paper is the first that has shown COVID-19 antibodies persist in breast milk for months following the mother’s vaccination,” she said.
Other preliminary data appears to support their work. Another recent study — which has not yet been peer-reviewed — looked at breast milk samples from 10 people who had been recently vaccinated with either the Moderna or Pfizer vaccine, and found significant levels of one specific antibody in them, called IgG.
Although more research is needed into the phenomenon, it echoes earlier research that found nursing mothers who tested positive for COVID-19 were delivering antibodies to their children through breast milk.
A study published in February that looked into the question reported that infants did not necessarily need to be separated from their mother if she contracted COVID-19.
“These early results suggest that breast milk from mothers who have had a COVID-19 infection contains specific and active antibodies against the virus, and that they do not transfer the virus through milk,” Bridget Young, one of the study authors and assistant professor in the Department of Pediatrics at the University of Rochester Medical Center, said in a press release.
The way that COVID-19 transmission or protection functions when it comes to pregnancy is a question that has persisted throughout the pandemic.
There were worries early on that pregnant people might pass COVID-19 to their unborn children. At least one study has shown that while mothers did not infect their children in utero, they did pass along antibodies to fight COVID-19.
Whether antibodies passed by a vaccinated or an infected parent give a child sufficient protection, and whether that protection lasts, are questions that still need to be answered.
But vaccine companies are working on extending their vaccines to children: Moderna is conducting clinical trials in Canada for children aged five to 11, while Pfizer’s data on the vaccine’s use in 12 to 15-year-olds will be reviewed by Health Canada in a couple of weeks.