Breastfeeding Mother and Child Clinical Outcomes After COVID-19 Vaccination

J Hum Lact. 2022 Feb;38(1):37-42. doi: 10.1177/08903344211056522. Epub 2021 Oct 29.


Background: Pre-approval clinical trials of the Pfizer/BioNTech messenger RNA COVID-19 vaccine, BNT162b2 did not include participants who were breastfeeding. Therefore, there is limited evidence about outcomes of breastfeeding mother-child dyads and effects on breastfeeding after vaccination.

Research aims: To determine: (1) solicited adverse effects (e.g., axillary lymphadenopathy, mastitis, and breast engorgement), which are unique to lactating individuals; and (2) systemic and local adverse effects of COVID-19 mRNA vaccine on mothers and potential effects on their breastfed infants.

Method: This was a prospective cohort study of lactating healthcare workers (N = 88) in Singapore who received two doses of BNT162b2 vaccination (Pfizer/BioNTech). The outcomes of mother-child dyads within 28 days after the second vaccine dose were determined through a participant-completed questionnaire.

Results: Minimal effects related to breastfeeding were reported by this cohort; three of 88 (3.4%) participants had mastitis, one (1.1%) participant experienced breast engorgement, five of 88 (5.7%) participants reported cervical or axillary lymphadenopathy. There was no change in human milk supply after vaccination. The most common side effect was pain/redness/swelling at the injection site, which was experienced by 57 (64.8%) participants. There were no serious adverse events of anaphylaxis or hospital admissions. There were no short-term adverse effects reported in the infants of 67 lactating participants who breastfed within 72 hr after BNT162b2 vaccination.

Conclusions: BNT162b2 vaccination was well tolerated in lactating participants and was not associated with short-term adverse effects in their breastfed infants.

Study protocol registration: The study protocol was registered at (NCT04802278).

Keywords: COVID-19; breastfeeding; cohort study; human milk; mRNA vaccines; mastitis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • BNT162 Vaccine
  • Breast Feeding
  • COVID-19 Vaccines*
  • COVID-19*
  • Female
  • Humans
  • Infant
  • Lactation
  • Mothers
  • Prospective Studies
  • SARS-CoV-2
  • Vaccination
  • Vaccines, Synthetic
  • mRNA Vaccines


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

Associated data