Can the messenger RNA from the Covid vaccine pass into breast milk? A study published in ‘Jama Pediatrics’ tries to answer this question. Scientists from New York University (NYU) Long Island School of Medicine say they have sporadically detected mRna in some of the samples taken in the milk of vaccinated mothers within 6 months of giving birth. However, 48 hours after vaccination, no more traces were identified. The cohort study was conducted on 11 healthy lactating women who received the Moderna (5) or Pfizer (6) vaccine. Participants were asked to immediately collect and freeze expressed breast milk (Ebm) samples. The collection was done before vaccination (control samples) and for 5 days after administration, starting one hour after shield injection. A total of 131 expressed breast milk samples were collected. And the analysis was conducted on different milk fractions: on the whole Ebm, on the fat part, on the cells and on the so-called extracellular vesicles. Result: Traces of both vaccines were found in 7 samples from 5 participants, taken at different times up to 45 hours after vaccination. On the other hand, no trace of vaccine mRna was detected in breast milk samples taken after 48 hours post vaccine. Furthermore, no mRna was detected in the milk fat fraction or in the cells. The researchers then observed that the vaccine’s mRna appears in higher concentrations in extracellular vesicles than in whole milk. “These data – underline the authors of the study, Nazeeh Hanna and colleagues – demonstrate, for the first time to our knowledge, the biodistribution of the mRna of the anti-Covid vaccine to breast cells and the potential ability of extracellular vesicles to ‘package’ the ‘mRna that can be transported to distant cells. We hypothesize that, after vaccine administration, the lipid nanoparticles containing the mRna are transported to the mammary glands by the hematogenous and / or lymphatic route. And we hypothesize that the mRna of the vaccine released in the breast cell cytosol can be recruited into the development of extracellular vesicles which are subsequently secreted into breast milk “. The” sporadic presence of traces of mRna in expressed breast milk suggests that breastfeeding after Covid vaccination is safe, in particularly after more than 48 hours “from the shield injection, conclude the scientists, suggesting caution regarding breastfeeding or breastfeeding infants under 6 months for the first 48 hours post maternal vaccination, until further safety studies are conducted. The work has limits (including numerical ones), the experts point out, who believe it is important to include breastfeeding people in future vaccination studies, to better evaluate the effect of mRna vaccines on this front. Potential interference with the immune response to multiple routine vaccines given to infants during the first 6 months of age should also be considered, they reflect.