Inactivation of Avian Influenza A(H5N1) Virus in Raw Milk at 63°C and 72°C

In March 2024, highly pathogenic avian influenza (HPAI) virus of A(H5N1) clade 2.3.4.4b was detected in mammalian livestock, mostly dairy cattle, in the United States and has now been reported in dairy herds in nine U.S. states.1 High titers of infectious virus and genome copies of HPAI A(H5N1) virus have been found in milk from these infected dairy cows.2 Molecular testing has also revealed the presence of HPAI A(H5N1) genetic material in approximately 20% of the samples obtained from retail pasteurized milk products, but researchers have been unable to culture virus from these samples.3 In this study, we measured the stability of HPAI A(H5N1) virus in raw milk at 63°C and 72°C, the temperatures most commonly used in commercial pasteurization.4