New research adds to the growing body of evidence that Covid-19 was unable to cause infection in the breastfed infant.
The study, published in the journal JAMA, examined 64 samples of breast milk collected by the ‘Mommy’s Milk Human Milk Research Biorepository’ from 18 women across the US infected with SARS-CoV-2.
Although one sample tested positive for viral RNA, subsequent tests found that the virus was unable to replicate, and thus unable to cause infection in the breastfed infant.
“Detection of viral RNA does not equate to infection. It has to grow and multiply in order to be infectious and we did not find that in any of our samples,” said study researcher Christina Chambers from the University of California, San Diego in the US.
“Our findings suggest breast milk itself is not likely a source of infection for the infant,” Chambers added.
The current recommendations to prevent transmission while breastfeeding is hand hygiene and sterilizing pumping equipment after each use.
“In the absence of data, some women infected with SARS-CoV-2 have chosen to just not breastfeed at all,” said study author Grace Aldrovandi form the University of California, Los Angeles.
“We hope our results and future studies will give women the reassurance needed for them to breastfeed. Human milk provides invaluable benefits to mom and baby,” Aldrovandi added,
Early breastfeeding is associated with a reduced risk of sudden infant death syndrome and obesity in children, as well as improved immune health and performance on intelligence tests.
In mothers, breastfeeding has been associated with lower risks for breast and ovarian cancer, cardiovascular disease and type 2 diabetes.
The researchers also mimicked conditions of the Holder pasteurization process commonly used in human donor milk banks by adding SARS-CoV-2 to breast milk samples from two different donors who were not infected.
The samples were heated to 62.5 degree Celsius for 30 minutes and then cooled to four degree Celsius. Following pasteurization, infectious virus was not detected in either sample.
“This is a very positive finding for donor milk, which so many infants, especially those born premature, rely on. Our findings fill in some important gaps, but more studies are needed with larger sample sizes to confirm these findings,” Chambers said.
The researchers said that future work will not only look at whether breast milk is free of the virus, but also whether it contains active antiviral components.
For example, antibodies to SARS-CoV-2 that women may produce after exposure to the virus and then transfer to their infants through breast milk, protecting them from Covid-19.
Earlier in this month, a study published in the Journal of Paediatrics and Child Health, found that pasteurising human milk inactivates the virus that causes Covid-19.