BNT162b2 mRNA vaccine elicited antibody response in blood and milk of breastfeeding women

Nat Commun. 2021 Oct 28;12(1):6222. doi: 10.1038/s41467-021-26507-1.


The importance of breastmilk in postnatal life lies in the strong association between breastfeeding and the reduction in the risk of infection and infection-related infant mortality. However, data regarding the induction and dynamics of breastmilk antibodies following administration of the Pfizer-BioNTech BNT162b2 COVID-19 mRNA vaccine is scarce, as pregnant and lactating women were not included in the initial vaccine clinical trials. Here, we investigate the dynamics of the vaccine-specific antibody response in breastmilk and serum in a prospective cohort of ten lactating women who received two doses of the mRNA vaccine. We show that the antibody response is rapid and highly synchronized between breastmilk and serum, reaching stabilization 14 days after the second dose. The response in breastmilk includes both IgG and IgA with neutralization capacity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antibody Formation / genetics
  • Antibody Formation / physiology
  • BNT162 Vaccine
  • Breast Feeding*
  • COVID-19 Vaccines / genetics*
  • Female
  • Humans
  • Milk / chemistry
  • RNA, Messenger / analysis
  • RNA, Messenger / blood*
  • Vaccines, Synthetic / therapeutic use


  • COVID-19 Vaccines
  • RNA, Messenger
  • Vaccines, Synthetic
  • mRNA Vaccine
  • BNT162 Vaccine