A new study found significant COVID-19 antibodies present in the breast milk of lactating parents who were either vaccinated or infected. 

Antibodies from both scenarios offer protection against severe COVID-related sickness, but the research does not imply nursing babies would receive substantial protection against the virus with breast milk alone.

Researchers still think the results are promising.  

“One of the exciting findings in this work is that breast milk from both mothers with COVID-19 infection, and from mothers receiving mRNA vaccination contained these active antibodies that were able to neutralize the virus,” said Bridget Young, an assistant professor in the Division of Pediatric Allergy and Immunology at University of Rochester Medical Center.

The URMC report, which was published in JAMA Pediatrics on Wednesday, analyzed the breast milk of 77 mothers. Of these two groups, 30 were vaccinated and 47 were previously infected with COVID. 

Researchers studied the milk for 90 days after vaccination or infection to find that the antibodies in both groups neutralize the virus.

The mothers with disease-acquired immunity produced high levels of Immunoglobulin A (IgA) antibodies against the virus, while vaccine-acquired immunity produced robust Immunoglobulin G (IgG) antibodies. 

Three months after vaccination, the study found a mild-to-modest decline in antibodies. 

“The trend in breast milk antibodies aligns with what we see in vaccination sera,” said study co-author Kirsi Jarvinen-Seppo, Chief of Pediatric Allergy and Immunology at URMC. “After a few months, the antibodies trend downward, but the levels are still significantly above what they were pre-vaccine.”

COVID-19 is rarely detected in human milk, which means it is unlikely to transmit to breastfed infants.

Children of all ages can get sick with COVID-19, but the severity can be rare. Most children have mild or no symptoms, but some can be hospitalized.

Research also found disproportionately higher rates of COVID-19 among Black children.