new research adds to the growing body of evidence that pasteurising human milk inactivates the virus that causes covid19while there is no evidence that the virus can be transmitted through breast milk there is always a theoretical risk said study lead author greg walker from the university of new south wales in australiaaccording to the study published in the journal of paediatrics and child health there are five human milk banks in australia as the covid19 pandemic evolves these milk banks continue to provide donated breast milk to preterm babies who lack access to their mothers own milkdonors are screened for diseases and the milk is tested and pasteurised to ensure that it is safe for medically fragile babiesweve seen in previous pandemics that pasteurised donor human milk pdhm supplies may be interrupted because of safety considerations so thats why we wanted to show that pdhm remains safe walker saidfor this study the team worked in the kirby institutes pc3 lab to experimentally infect small amounts of frozen and freshly expressed breast milk from healthy lifeblood milk donors they then heated the milk samples now infected with sarscov2 to 63 degree celsius for 30 minutes to simulate the pasteurisation process that occurs in milk banks the study found that after this process they did not contain any infectious live virusour findings demonstrate that the sarscov2 virus can be effectively inactivated by pasteurisationthe researchers say their experiments simulated a theoretical worstcase scenariothe amount of virus we use in the lab is a lot higher than what would be found in breast milk from women who have covid19 so we can be really confident of these findings walker saidthe researchers also tested if storing sarscov2 in human milk at four degrees celsius or 30 degree celsius would inactivate the virus the first time a study has assessed the stability of experimentallyinfected coronavirus in human milk under common storage conditionswe found that cold storage did not significantly impact infectious viral load over a 48hour period the study authors wrotewhile freezing the milk resulted in a slight reduction in the virus present we still recovered viable virus after 48 hours of storage they notedearlier in july a canadian study published in the journal cmaj found that pasteurising breast milk using a common technique inactivated the covid19 virus