By Dr. Sanchari Sinha Dutta, Ph.D. Reviewed by Lauren Hardaker Oct 14 2025 Researchers discovered that the H5N1 bird flu virus can persist for up to 120 days in raw-milk cheese, challenging long-standing safety rules and raising new questions about the risks of unpasteurized dairy. Study: H5N1 influenza virus stability and transmission risk in raw milk and cheese . Image credit: Parilov/Shutterstock.com A new study published in Nature Medicine reveals that highly pathogenic avian influenza