On December 20, 2020, Israel started a national vaccination program against COVID-19. One prioritized group was health care workers. Many workers were breastfeeding women. In the U.S., the Centers for Disease Control and Prevention (CDC) has also recommended that breastfeeding women be vaccinated.
Measuring antibodies in breastmilk
Researchers from Israel looked at breastfeeding women who received the Pfizer vaccine. They collected samples of breast milk before the vaccination, and also 2 weeks after the dose every week for 6 weeks. In this study, 84 women provided 504 breast milk samples. Researchers measured antibodies in the breast milk, as antibodies protect babies against the virus that causes COVID.
Good response to COVID vaccination in breastfeeding mothers
The researchers found that IgA antibodies (the early antibody) against the virus that causes COVID increased very quickly 2 weeks after the first dose of the vaccine (62% of samples showed antibodies). This increased to 86% after 4 weeks (just as the second dose was given). After this, the antibody levels remained high, and the IgA ones were replaced by IgG antibodies – these are the ones that protect for much longer. The IgG antibodies were found in 97% of the breast milk samples by 5 weeks. Importantly, no mother or baby had any serious negative side effects.
This study found good production of IgA and IgG antibodies in breast milk after vaccination. These antibodies protect babies against COVID. Other studies have shown similar findings in women infected with COVID.
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