FDA assures safety of commercial milk supply from H5N1 HPAI

Over the past few months, with the surge in highly pathogenic H5N1 avian influenza (H5N1 HPAI) in raw milk, the FDA has been working to assess the safety of the commercial food supply. Last week, the administration issued an update with data from a government-facilitated study assuring the public that the commercial milk supply is safe.

The study conducted by the administration assessed how commercial milk processing protocols, including typical pasteurization times and temperatures.

Researchers collected 275 raw milk samples from farms across four states to understand and assess viral levels in the unpasteurized milk supply that would be commercially processed. Among the samples collected, 158 were positive for viral fragments, and 39 had 3,000 virus particles per milliliter, indicating a relatively high viral presence.

Using this data, researchers artificially contaminated homogenized raw whole milk with H5N1 HPAI concentrations greater than those naturally found in the commercial supply. These samples then went through continuous-flow processing of the milk at 161°F (72°C) for 15 seconds. This process, sometimes called high-temperature-short-time  or flash pasteurization, is the most common pasteurization strategy utilized by the dairy industry as required by the Code of Federal Regulations  and the Pasteurized Milk Ordinance .

“This commercial milk processing simulation study is notably different than some recent benchtop studies published by other institutions which have shown mixed results regarding the sensitivity of the virus to thermal treatment,” said Stephen Walker, PhD, PE, Consumer Safety Officer, in the FDA’s Center for Food Safety and Applied Nutrition, in the FDA press release.

According to the press release, the virus was completely inactivated in the spiked milk samples after the flash pasteurization.

 “Other recent studies relied on benchtop equipment that was likely not sufficient to accurately simulate high-temperature-short-time  processing conditions. In contrast, the results of the study announced today strongly indicate that the virus is much more sensitive to heat treatment with commercial pasteurization equipment than other studies might suggest.”

Beyond that, the experiments indicated that the inactivation process occurs rapidly, as many samples collected in the middle of the pasteurization process already had a reduced concentration of the active virus. 

“While testing finished product post-pasteurization is one strategy to detect potential problems in finished products, validating the effectiveness of the pasteurization parameters critically demonstrates that commercial milk processing is capable of controlling the HPAI virus and further provides broad assurance that pasteurized milk and dairy products made from pasteurized milk are safe,” said Nathan Anderson, PhD, Director, Division of Food Processing Science and Technology in the FDA’s Center for Food Safety and Applied Nutrition.