A study conducted by the USDA Agricultural Research Service has determined that cooking ground beef to a temperature of 145 F is adequate to eliminate the viability of H5N1 influenza virus in patties.
Beef patties of 300 g were spiked with an H5N1 surrogate influenza virus and then were cooked. The study compared temperatures of 120 F, 145 F and 160 F. The lowest temperature of 120 F “substantially inactivated” the virus. No viable virus was detectable in patties cooked at either145 F or 160 F. Standard recommendations are to cook patties and chicken products to 165 F to destroy non-spore forming bacterial pathogens including Salmonella.
The study conducted by USDA-ARS confirmed that existing recommendations should inactivate H5N1 and presumably other influenza A viruses. The USDA Food Safety and Inspection Service is currently collecting beef muscle from culled dairy cows condemned at ante mortem inspection at 
plants to determine the prevalence of H5N1 virus. To date one isolate of H5N1 has been obtained. It is noted that culled dairy animals represent approximately six percent of the U.S. beef supply and are mostly processed into ground beef.