Can mRNA vaccine be found in breastmilk?

New research is investigating whether the mRNA from COVID-19 vaccines can be passed on to infants through breast milk.

The development and delivery of SARS-CoV-2 vaccines help reduce the transmission of COVID-19, and these vaccines are an essential part of fighting the global COVID-19 pandemic. The first approved SARS-CoV-2 vaccines were mRNA vaccines, which use mRNA from the SARS-CoV-2 spike protein to train the immune system to recognize the pathogen without the risk of COVID-19 infection and to attack. 1

The two mRNA vaccines currently approved for COVID-19 are BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna). Current research suggests that both vaccines are highly effective in preventing COVID-19; BNT162b2 has an efficacy rate of 95% and the vaccine mRNA-1273 has an efficacy rate of 94.1% .2,3,4,5 Studies of these vaccines also suggest that both have excellent safety profiles and a low risk of serious side effects .4.5

Are mRNA Vaccines Safe for Breastfeeding Women?

Breastfeeding or breastfeeding women can receive both Pfizer and Moderna vaccines, and the World Health Organization (WHO) recommends the use of these vaccines in breastfeeding women.2,3 This recommendation is also supported by other major health organizations, including the Academy of Breastfeeding Medicine and Centers for Disease Control and Prevention, which states that there is no significant plausible risk that the vaccine will alter breast milk or tissues.6,7

This recommendation is based on some facts about the mRNA vaccine; the mRNA vaccine does not contain live virus, the mRNA molecules do not alter the DNA in the cell nucleus and the mRNA is broken down relatively quickly in the body.2,3

Studies in pregnant animals did not reveal any safety concerns for mothers or babies.7 However, since there are ethical concerns about the participation of pregnant and breastfeeding women in clinical trials due to the potential risk to the health of the mother or fetus, data from clinical trials are currently available on the safety profile of the mRNA vaccine in breastfeeding women.

Is vaccine mRNA found in breast milk?

A study should provide information on whether parts of the mRNA vaccine were found in human breast milk after vaccination

The researchers collected 13 milk samples from seven breastfeeding mothers up to 48 hours after vaccination. The mean age of the participants was 37.8 years, and the ages of their children varied between one month and three years.8 The samples were frozen immediately for preservation and the polymerase chain reaction (PCR) samples were tested for those in the Pfizer and Moderna Vaccines. 8 The test results were analyzed and compared to milk samples from four of the participants before they received the vaccine to serve as a comparison group. 8

In the study, no evidence of mRNA from the vaccines was reported in any of the samples.8 This suggests that no mRNA from the vaccines was transferred to breast milk or infants in this group.

It is important to note that this study was conducted with a small sample size, which could limit the generalizability of the results. Further studies in larger populations are needed to determine whether vaccine-associated mRNA could be passed on in breast milk.


  1. Centers for Disease Control and Prevention (2021 May 27). Available vaccines. US Department of Health and Social Welfare. Accessed July 21, 2021 from
  2. World Health Organization (2021 June 15). Preliminary recommendations for using the Pfizer-BioNTech COVID-19 vaccine, BNT162b2, below the emergency list. World Health Organization. Accessed July 21, 2021 at
  3. World Health Organization (2021 June 15). Preliminary recommendations for using the Moderna mRNA-1273 vaccine against COVID-19. World Health Organization. Retrieved July 21, 2021 from
  4. Polack, F.P., Thomas, S.J., Kitchin, N., et al. (2020, December 31). Safety and effectiveness of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med 383: 2603-2615. Doi: 10.1056 / NEJMoa2034577.
  5. Baden, L.R., El Sahly, H.M., Essink, B., et al. (2021, February 4th). Effectiveness and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med 384: 403-416. Doi: 10.1056 / NEJMoa2035389
  6. Academy for Breastfeeding Medicine (2020, December 14th). Considerations for COVID-19 vaccination while breastfeeding. Academy for Breastfeeding Medicine; Chicago, USA, accessed July 21, 2021 at
  7. Image by Rainer Maiores from Pixabay

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