COVID-19 infection and vaccination in pregnant women can result in significant antibodies in breast milk that exhibit different temporal patterns, but both neutralize the live SARS-CoV-2 virus, according to a study by researchers at the University of Rochester Medical Center and New York University.
The analysis published in the journal JAMA Pediatrics, reports that the study included a convenience sample of 47 lactating pregnant women who had been infected with the virus, in addition to another 30 who were vaccinated against COVID-19.
In the case of breast milk from those who were infected with COVID, the amount of antibodies was dominant and highly variable, while in those who were vaccinated, it was associated with a strong antibody response that began to decline 90 days after the second vaccine dose.
However, milk from both groups showed neutralizing activity against the live SARS-CoV-2 virus, with slow antibody loading of IgA, which is found in the linings of the respiratory tract and digestive system, as well as in saliva, tears and breast milk, and IgG, which are the most abundant antibodies in the body.
“It’s one thing to measure antibody concentrations, but it’s another to say that the antibodies are functional and can neutralize the SARS-CoV-2 virus. One of the exciting findings of this work is that the breast milk of both mothers with COVID-19 infection and mothers who received the mRNA vaccine contained these active antibodies that were capable of neutralizing the virus,” said Dr. Bridget Young, one of the study’s lead authors.
"Our data suggest that both IgA and IgG contribute to the neutralizing capacity, implying a clinical benefit for infants receiving breast milk from mothers with COVID-19 infection or who are vaccinated," the document highlights.
This study has the longest follow-up of breast milk after vaccination compared to previously published studies.
“Importantly, whether a dominant IgA or IgG response, both infection and vaccination generated human milk with neutralizing activity. Among other benefits, breast milk provides protection against morbidities, including respiratory and diarrheal diseases, due to specific and nonspecific immune factors, including antibodies,” the study states.
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