Can breastfeeding replace the vaccine?

The kind of immunity transferred through breastfeeding is different from the immunity of babies in utero,  which is passed through the placenta or umbilical cord. In the latter case, it is immunoglobulin G (IgG), which is contained in the blood and bodily fluid, and, once passed to the fetus’s body, protects it from infection for a few months. Breast milk carries a immunoglobulin A (IgA), which is found in the mucous membranes such as those lining the nose or throat, and stops the virus locally.

“Breastfed babies would gain mucosal immunity through breastfeeding because the milk gets all over their nasal passages in the oral and nasal cavities where the virus could enter, and can neutralize it directly in that area,” says Edlow. These kinds of antibodies, however, aren’t transferred into the baby’s bloodstream, and while it might offer some protection in the digestive tract, the immunity is short-lived, ending when the child is no longer breastfed.

New mothers who didn’t receive the vaccine during pregnancy and do so after delivery can—and should—breastfeed their babies, because a little immunity is better than no immunity.

Does breast milk provide immunity if drunk by older children?

Edlow says she is often asked whether feeding breast milk to older children—especially those under five for whom the vaccine isn’t yet authorized—gives them some level of immunity. While there isn’t specific covid-19 research on that, she says it very likely wouldn’t, due to the way milk from breastfeeding enters into the nasal passage and mouth, providing IgA immunity. Drinking milk would deliver the antibodies only to the digestive tract, but leave the nasal ways open for the virus to enter the body.

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