You have asked us through our WhatsApp verification service for a study reporting the detection of mRNA from covid vaccines in breast milk. Is researchpublished in the scientific journal JAMA Pediatrics on September 26, it has gone viral on Facebook and Twitter accompanied by messages suggesting that it is something dangerous for infants. However, these are not the conclusions of the work.
Both the authors of the study and the specialists consulted by Newtral.es state that the amount of mRNA found in breast milk is “tiny” and that are not significant amounts to pose any danger to the safety of breastfeeding after vaccination. In addition, they insist that mRNA is a molecule that is very easily degraded, so it has no effect on the child.
Study detected mRNA in breast milk, but in few samples
as already we have explained in Newtral.es, Pfizer’s covid vaccine, like Moderna’s, is based on messenger RNA or mRNA technology, which contains the instructions to synthesize protein S, a protein of the SARS-CoV-2 coronavirus. When the mRNA enters the cells, this protein is made, which is then recognized by our immune system and generates defenses. Thus, in case of contagion, our body will know how to defend itself.
This mRNA is what the study has detected in breast milk. The work involved 11 people who donated breast milk at different times before and after vaccination, and obtained 131 samples in total.
But the important thing, as Africa González, Professor of Immunology at the Biomedical Research Center (CINBIO) of the University of Vigo, explains to Newtral.es, is that “only in seven of the 131 samples were traces of RNA found, and in very very low amounts.
Victoria Male, a reproductive immunologist at Imperial College London, also underlines in statements to SMC Spain that the amounts were very small, 11 parts per billion. “This equals a single tear in an Olympic pool”, he points out. Matilde Cañelles, an immunologist at the Higher Council for Scientific Research (CSIC), also states that the amounts are “so low that they are below what other studies consider significant.” In addition, as reported in the study itself, at 48 hours they stopped seeing mRNA in the samples at all.
In fact, one of the authors of the text, Nazeeh Hanna, head of neonatology at NYU Langone Health Hospital, told Newtral.es that his results do not question the safety of vaccines. “We believe that breastfeeding after vaccination is safe because we only found small traces of mRNA. Furthermore, this mRNA is not shown to be biologically active.” These conclusions are also written in the text of the study that has been shared.
mRNA found in breast milk, with no chance of affecting the baby
With such low levels, the mRNA found cannot affect the infant. That is the opinion of Jesús Ruiz Contreras, a medical member of the Vaccine Advisory Committee of the Spanish Association of Pediatrics (CAV-AEP): “These amounts they don’t stand a chance per se to stimulate the child’s immune system or harm the baby”.
Furthermore, Ruiz argues that these conclusions are not new. According to the doctor, another study, published in the magazine Frontiers in Immunology in January 2022, it also found “occasional” amounts of mRNA in breast milk and concluded that “no evidence was found that they were passed on to the child.”
and other work published in August 2021 in the magazine NPJ Vaccines reported that it found mRNA for the vaccine in some of the breast milk samples, “indicative of minimal transfer.” Thus, they conclude that the results “define the safety of vaccines in this demographic group.” The authors also state that their research supports recommendations against interrupting lactation for vaccination with mRNA vaccines.
For this reason, the member of the AEP continues to affirm that breastfeeding after vaccination is safe.
Residual RNA will be degraded
In the text, the authors state that the amounts of mRNA found are very small, but that they have not evaluated a possible accumulation in the infant. However, the AEP doctor recalls that RNA is a molecule “very easy to degrade.”
“If the RNA enters the baby orally, it will be easily broken down by enzymes in the mouth or digestive system”, it states. González, an immunologist at the University of Vigo, agrees: “Any residual RNA that might exist in breast milk is degraded by the child’s gastrointestinal system.”
González also affirms that there will always be more viral RNA in the event that the mother is infected with covid than when she has received the vaccine, although it was shown that it could not generate an infection in the child.
“And study published in the magazine Nature Last January, with 110 lactating women, it concluded that viral RNA was detected in breast milk in 6% of women with confirmed covid infection. However, the virus capable of generating infection was not detected in any of the samples”, she points out.
What is in breast milk: antibodies against covid that protect the baby
Ruiz recalls that what is found in breast milk in significant quantities are the antibodies against covid. “Whether the mother has been vaccinated or if she has generated immunity from being infected, the antibodies against covid are passed to the baby through breast milk and protect him,” he points out.
Both the study published in Frontiers in Immunology like the one posted on NPJ Vaccines mentioned above found antibodies capable of neutralizing SARS-CoV-2 in breast milk. According to the authors of both studies, this is early evidence that mothers can transfer immunity against covid to infants through milk.