Is the COVID-19 (Coronavirus Disease 2019) vaccine transmissible via breast milk?

From the Guidelines

No, COVID-19 vaccines are not transmissible through breast milk, and mothers can safely continue breastfeeding after vaccination. The current evidence suggests that vaccine-related mRNA has not been detected in early breast milk studies, and no plausible mechanism of neonatal harm has been identified 1. In fact, experts from the Academy of Breastfeeding Medicine and the American College of Obstetricians and Gynecology (ACOG) agree that vaccination poses minimal to no potential risk to the newborn.

The benefits of vaccination during lactation may include the passage of vaccine-stimulated immunoglobulin A through breast milk, providing additional protection against SARS-CoV-2 infection to the infant 1. The safety of COVID-19 vaccines for lactating women seems reassuring, with no reason to suspect that receipt of the vaccine would lead to any adverse neonatal effects or harmful changes to lactation.

Key points to consider:

• Vaccine-related mRNA is not detected in breast milk 1
• No plausible mechanism of neonatal harm has been identified 1
• Vaccination during lactation may provide protective antibodies to the infant 1
• Health authorities recommend vaccination while breastfeeding due to its potential benefits 1

From the FDA Drug Label

It is not known whether Pfizer-BioNTech COVID-19 Vaccine is excreted in human milk. Data are not available to assess the effects of Pfizer-BioNTech COVID-19 Vaccine on the breastfed infant or on milk production/excretion

• The Pfizer-BioNTech COVID-19 Vaccine does not have sufficient data to determine if it is excreted in human milk.
• There is no information available on the effects of the vaccine on the breastfed infant or on milk production/excretion 2. The FDA drug label does not answer the question.

From the Research

Covid Vaccine Transmission via Mother's Milk

• The Covid vaccine is not transmissible via mother's milk in a way that would cause harm to the infant, as stated in the study 3.
• Although small quantities of mRNA may be detectable in breast milk after maternal vaccination, there is no evidence that vaccine mRNA can survive the infant gastrointestinal tract 3.
• The breast milk of vaccinated individuals contains SARS-CoV-2-specific functional antibodies and T cells, which benefit the breastfeeding infant's developing immune system 3.
• Studies have shown that breast milk from mothers who have received vaccinations can transfer antibodies, providing immune protection for the breastfeeding infant 4, 5.
• The presence of antibodies in human milk after COVID-19 vaccination has been observed, with a moderate association between higher titers of IgG and a longer duration of breastfeeding 6.
• Trace amounts of COVID-19 vaccine mRNA have been detected in breast milk, but its integrity is reduced and it does not express SARS-COV-2 spike protein or induce its expression in cells 7.

Safety of Breastfeeding after Covid Vaccination

• The Centers for Disease Control and Prevention and the American College of Obstetricians and Gynecologists recommend that lactating individuals receive COVID-19 mRNA vaccines and stay up to date on booster doses 3.
• Numerous studies demonstrate that the breast milk of vaccinated individuals contains SARS-CoV-2-specific functional antibodies and T cells, which benefit the breastfeeding infant's developing immune system 3, 4, 5.
• There is no evidence to suggest that breastfeeding should be avoided after Covid vaccination, and the benefits of breastfeeding outweigh any potential risks 3, 7.