The Pfizer-BioNTech Covid-19 vaccine promotes the production of antibodies in mothers’ breastmilk, potentially contributing to the protection of their nursing babies.

That is the conclusion of a study of 10 breastfeeding mothers conducted by Tel Aviv University and Tel Aviv Sourasky Medical Center during January and February soon after the vaccines arrived in Israel.

The volunteers received two shots of the vaccine, 21 days apart, and the levels of antibodies in both their blood and breastmilk were tested at four points in time, following vaccination.

Results indicate that antibodies generated by the vaccine are well synchronized in the blood and breastmilk. Both showed a significant increase 14 days after the first dose and continuing seven days after the second dose.

The researchers also found that the antibodies found in the breastmilk may block the virus from binding with receptors on host cells.

Lead researcher Dr. Yariv Wine said, “The encouraging data show that vaccinating breastfeeding mothers promotes the production of important antibodies in their breastmilk, potentially protecting their nursing babies from the disease.”

The paper about the study is currently undergoing peer review.

The research team included PhD student Aya Kigel from the Shmunis School of Biomedicine and Cancer Research at TAU; and a group from the Lis Maternity and Women’s Hospital at the Tel Aviv Sourasky Medical Center led by Dr. Michal Rosenberg-Friedman and Prof. Ariel Many.