Pasteurising breast milk inactivates COVID-19 virus: Study

Researchers have found that pasteurising breast milk using a common technique inactivates severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) making it safe for use.

According to the study, published in the CMAJ (Canadian Medical Association Journal), current advice is for women with coronavirus disease 2019 (COVID-19) to continue to breastfeed their infants.

In Canada, it is standard care to provide pasteurised breast milk to very-low-birth-weight babies in the hospital until their own mother's milk supply is adequate.

"In the event that a woman who is COVID-19-positive donates human milk that contains SARS-CoV-2, the method of pasteurisation renders milk safe for consumption," said study researcher Sharon Unger from the University of Toronto in Canada.

"Whether by transmission through the mammary gland or by contamination through respiratory droplets, skin, breast pumps and milk containers, this method is safe," Unger added.

The Holder method, a technique used to pasteurise milk in all Canadian milk banks (62.5 degree C for 30 minutes), is effective at neutralising viruses such as HIV, hepatitis and others that are known to be transmitted through human milk.

In this study, researchers spiked human breast milk with a viral load of SARS-CoV-2 and tested samples that either sat at room temperature for 30 minutes or were warmed to 62.5 degree C for 30 minutes and then measured for the active virus.

The study found that the virus in the pasteurised milk was inactivated after heating.

More than 650 human breast milk banks around the world use the Holder method to ensure a safe supply of milk for vulnerable infants, the researchers said.

The authors reported that the impact of pasteurisation on coronaviruses in human milk has not been previously reported in the scientific literature.