There is a claim that infants gain immunoprotection from breastfeeding. I am especially interested in specific protection against pathogens the breastfeeder (not necessarily the mother) has been vaccinated against intramuscularly.

While I know, that IgA and IgM may be present in breast milk and provide passive protection against foodborne pathogens, it is unclear to me, whether there would be any synthesis (and transport to breast milk) of those antibodies without contact between the pathogen and a mucosal membrane of the breastfeeder. Answer to my previous question suggest that there would be no IgA production as signals received by B-cells in a muscle will lead mostly to IgG synthesis.

I am not asking about the transplacental transport of IgG, only about breastfeeding.


1 Answer 1


Vaccinating the mother or a breastfeeder to provide immunization for the baby through breastfeeding is not proven nor recommended by health authorities.

If a mother is vaccinated intramuscularly or any other route, it will anyway pass IgA and IgM, and to a much lesser extent IgG antibodies to the baby through breastmilk but it is not proven to confer specific immunity against all pathogens.

And as per your other question, a child from a mother who hasn't had any infection/vaccination with Hepatitis A and hasn't passed any IgG through the placenta will not be conferred immunity against Hepatitis A even if it is breastfed from a woman who had the infection or was vaccinated against Hepatitis A.

There are other ways a mother's breastmilk can induce immunity (cell immunity) this is currently under research and it has been proven to confer immunity in animal models in recent studies but is still not a medical recommendation in humans (studies in pups regarding passing immunity through foster breastmilk for candida albicans , tuberculosis and helminth infections).

What is already proven is that breasfeeding and vaccination of the baby does provide with a more robust vaccination response so that is why breastfeeding and vaccination to the baby at the same time are encouraged.

Maternal Milk T Cells Drive Development of Transgenerational Th1 Immunity in Offspring Thymus

Pre-conception maternal helminth infection transfers via nursing long-lasting cellular immunity against helminths to offspring

  • $\begingroup$ May you point me to the source of the claim that intramuscular immunization leads to transport of specific IgA/IgM to breastmilk? The answer I linked in the question suggests there is no synthesis of specific IgA. $\endgroup$
    – abukaj
    Commented Jun 30, 2020 at 13:30

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