If the mother is vaccinated against Covid-19, her milk protects the baby by offering him an effective defense against Sars-CoV-2 even when he is too small to be vaccinated. To provide new evidence on thevaccine shield effect ‘transmitted’ from mother to child through breastfeeding is a study by the University of Florida, reported in the ‘Journal of Perinatology’ and funded by the Children’s Miracle Network and the Gerber Foundation. After discovering and publishing in 2021 that vaccinated mother’s milk contained anti-Covid antibodies, by analyzing the feces of breastfed infants, American scientists have now shown that these antibodies actually protect the baby.
“Our first study showed that in the milk of vaccinated women there were antibodies to Sars-CoV-2, but we couldn’t tell if those antibodies crossed the children’s gastrointestinal tract providing them with protection,” explains Joseph Larkin III, senior author of the paper. Now the researchers have verified this, using a technique called neutralization test.First, antibodies for Sars-CoV-2 were isolated from the feces of breastfed infants from mothers vaccinated against Covid-19.These antibodies were then added to a line of cells presenting the receptors used by the pandemic coronavirus to mount its attack. Finally, everything was exposed to a Sars-CoV-2 pseudovirus that acts like the real pathogen, but is safer to handle in the laboratory. The pseudovirus is fluorescent, so when it binds to a cell, it lights up.
In this way “we saw that, in the presence of antibodies” from vaccinated mother’s milk, “there were fewer fluorescent cells than” those observed in “controls with no antibodies”, reports Lauren Stafford, one of the first authors of the article . That’s because “the antibodies interfere and don’t let the virus get to the cells,” comments Larkin. In other words, vaccine-induced antibodies present in breast milk offer real protection to the baby. “Antibodies ingested through breast milk can provide a protective lining in the mouth and gastrointestinal tract of infants,” confirms Vivian Valcarce Luaces, one of the first authors of the study.
The scientists also measured and tested the antibodies present in the mothers’ plasma and milk immediately after the anti-Covid vaccination and 6 months later, finding that they were more able to neutralize the virus, although the antibody levels decreased after 6 months, as moreover indicated by other studies on vaccines.
Returning to the antibodies found in the faeces of babies breastfed by vaccinated mothers, “in our research – comments Josef Neu, one of the co-authors of the study – we are following the journey of the antibodies from when they are produced in the mother after vaccination to when they cross the digestive system of the son. The next question” to be answered “is whether these children”, thanks to the antibodies ‘inherited’ from the vaccinated mother, “are less likely to contract Covid”.
According to the researchers, larger investigations are needed to understand this. This study in fact included 37 mothers and 25 children, relatively small numbers which however add – the authors remark – to the growing evidence based on which vaccination against Covid-19 during pregnancy and breastfeeding can protect newborns.