COVID-19 infection and vaccination in pregnant women can result in significant antibodies in breast milk that exhibit different temporal patterns, but both neutralize 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 PediatricsThe study included a convenience sample of 47 pregnant infants who had been infected with the virus, in addition to 30 others who were vaccinated against COVID-19.
In the case of breast milk from those who were infected with COVID, the amount of antibody was dominant and highly variable, while in those who were vaccinated, it was associated with a robust antibody response that began to decline 90 days after the second dose of vaccine.
However, milk from both groups showed neutralizing activity against live SARS-CoV-2 virus, and with slow loading of IgA antibodies, which are 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 breast milk from both mothers with COVID-19 infection and mothers who received the mRNA vaccine contained these active antibodies that were able to neutralize 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 who receive breast milk from mothers with COVID-19 infection or who are vaccinated," the paper notes.
This study has the longest follow-up of breast milk after vaccination compared to previously published studies.
"Importantly, whether IgA or IgG dominant, 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 notes.
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