Scientists have found that pasteurisation of human milk inactivates the novel coronavirus that causes COVID-19. The development can help form guidelines around safe expressing and storing milk from mothers infected with the deadly virus.
However, the study noted that breastfeeding is still safe for coronavirus positive mothers and added that there is no evidence to suggest the SARS-CoV-2 virus can be transmitted via breast milk. The study has published in the Journal of Paediatrics and Child Health.
“While there is no evidence that the virus can be transmitted through breast milk, there is always a theoretical risk,” said Greg Walker, lead author of the study from UNSW.
“We’ve seen in previous pandemics that pasteurised donor human milk (PDHM) supplies may be interrupted because of safety considerations, so that’s why we wanted to show that PDHM remains safe,” Walker said.
In the study, the scientists – including those from the University of New South Wales (UNSW) in Australia – experimentally infected small amounts of frozen and freshly expressed breast milk from healthy donors.
“We then heated the milk samples — now infected with SARS-CoV-2 – to 63 degree Celsius for 30 minutes to simulate the pasteurisation process that occurs in milk banks, and found that after this process, they did not contain any infectious, live virus,” Walker said.
“Our findings demonstrate that the SARS-CoV-2 virus can be effectively inactivated by pasteurisation,” he added.
According to the scientists, the experiments simulated a theoretical worst-case scenario.
“The amount of virus we use in the lab is a lot higher than what would be found in breast milk from women who have COVID-19 — so we can be really confident in these findings,” Walker added.
Laura Klein, a senior study author, said the purpose of the research was to provide evidence behind what people already expected.
“Pasteurisation is well known to inactivate many viruses, including the coronaviruses that cause SARS and MERS. These findings are also consistent with a recent study that reported SARS-CoV-2 is inactivated by heat treatment in some contexts,” she said.
The researchers also tested if storing SARS-CoV-2 in human milk at 4 or -30 degree Celsius would inactivate the virus, which they said is the first time a study has assessed the stability of experimentally infected SARS-CoV-2 in human milk under common storage conditions.
“We found that cold storage did not significantly impact infectious viral load over a 48-hour period,” Walker said.
“While freezing the milk resulted in a slight reduction in the virus present, we still recovered viable virus after 48 hours of storage,” he added.
