Lactating women who undergo vaccination for COVID-19 are doing a favor not only to themselves but also to their infants, according to a new study conduced at Tel Aviv University (TAU) and Tel Aviv Sourasky Medical Center. 

The new research, just published online in the preprint MedRxiv under the title “COVID-19 mRNA vaccine elicits a rapid and synchronized antibody response in blood and milk of breastfeeding women” and now undergoing peer review, found that the vaccination of breastfeeding women against the Coronavirus encourages the production of important antibodies in breast milk that can help protect the nursing baby. 

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The leading team of researchers at Tel Aviv University included Dr. Yariv Wine and doctoral student Aya Kigel from the TAU’s School of Biomedical and Cancer Research in its Faculty of Life Sciences and Dr. Michal Rosenberg Friedman and Prof. Ariel Many and colleagues from the medical center’s Lis Maternity and Women’s Hospital.

According to the researchers, the aim of the study was to determine whether Pfizer’s Corona vaccine is effective in producing antibodies in breast milk and what the qualities of these antibodies are, including whether they have the ability to neutralize the virus. 

The study was conducted in January and February of this year, when the vaccines began to arrive in Israel. The study included 10 breastfeeding women who volunteered to get the vaccine in two doses three weeks apart. Antibody levels in their blood and milk were tested at four points of time after the vaccination. 

“We describe the dynamics of the vaccine-specific antibody response in the breastmilk and serum in a prospective cohort of ten lactating women who received two doses of the Pfizer-BioNTech COVID-19 mRNA vaccine,” they wrote. “The antibody response was rapid and highly synchronized between breastmilk and serum, reaching stabilization 14 days after the second dose. The predominant serum antibody was IgG. The response in the breastmilk included both IgG and IgA with neutralizing capacity.”

The study showed that the increase in the levels of antibodies specific for the vaccine is well coordinating between the blood and milk, with a significant increase in blood and milk 14 days after the first dose that continued to grow a week after the second dose. 

The researchers also found that the antibodies that develop in milk have the ability to block the binding of the virus to the receptor on the storage cell and are important for preventing disease in the baby 

“Overall, the encouraging data show that giving the Corona vaccine to breastfeeding women encourages the production of important antibodies in breast milk that can contribute to the protection of the breastfed baby,” concluded Wine.