Live H5N1 avian influenza can survive in meat cooked rare, the US Department of Agriculture (USDA) has found.
In a study conducted this week, USDA scientists discovered that hamburgers cooked at 120 degrees Fahrenheit – the temperature of a rare steak – contained live traces of a substitute bird flu virus.
Whether the amount of virus found would be enough to infect a human is still unclear, but experts are concerned that – as H5N1 continues to spread through US cattle – rare and raw meat might provide a possible transmission route.
The USDA, which has faced criticism for insufficient information sharing during the ongoing bird flu outbreak, presented their findings at a press briefing earlier this week but initially failed to disclose that the virus was found in samples of rare meat.
During the briefing, the agency said that no virus was present in burgers cooked to 145 degrees (medium rare) or 160 degrees (well done) – but only mentioned that traces of virus were found in burgers cooked to 120 degrees when questioned by journalists.
While H5N1 has only been found in America’s dairy herds so far, some cattle are repurposed for beef when “retired” from milk production.
Because the cows aren’t specifically bred for meat, they are often cheaper – meaning their meat is primarily turned into low-quality ground beef – the kind you’d find in a fast-food restaurant.
The USDA said that it is yet to find traces of H5N1 in slaughterhouse cows or retail beef, but wanted to better understand the effectiveness that cooking has on killing the virus.
The agency advises that consumers cook their ground beef to an internal temperature of 160 degrees Fahrenheit – which is classified as ‘well done’ – to avoid infections from bacteria like salmonella or E.Coli.
But in practice, this advice rarely plays out – consumers and restaurants can cook their meat however they like.
“People often consume undercooked meat, especially beef, so full study results are crucial for informed decisions and building trust with the public,” Dr Krutika Kuppalli, a spokesperson for the Infectious Disease Society of America and former WHO medical officer, said on X (formerly Twitter) .
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