Experiments by researchers from the National Institute of Allergy and Infectious Diseases (NIAID) on milk samples spiked with H5N1 avian influenza found that levels rapidly decline when heated to pasteurization temperatures, but small amount of infectious virus remain.

The team reported its findings today in a letter to the New England Journal of Medicine, and they emphasized that the findings reflect experimental lab conditions and don't reflect large-scale industrial pasteurization of raw milk.

Using virus isolated and grown from a mountain lion that died from H5N1 in Montana, they mixed the virus with raw cow milk samples, then heated them to 63°C (145.4°F) and 72°C (161.6°F), the temperatures most commonly used in commercial pasteurization, for different periods. Then they cultured the milk sample to see if any infectious virus remained.

Findings should not be used to judge safety of US milk supply

Heating the milk to 63°C led to a tenfold decrease in H5N1 levels after 2.5 minutes, and they noted that standard pasteurization of 30 minutes would eliminate infectious virus. Heating the milk to 72°C decreased virus levels fourfold within 5 seconds, but they detected very small levels of infectious virus after 20 seconds in one out of three samples.

"This finding indicates the potential for a relatively small but detectable quantity of H5N1 virus to remain infectious in milk after 15 seconds at 72℃ if the initial virus levels were sufficiently high," the group wrote.

Researchers emphasized that the conditions should be replicated with commercial pasteurization equipment and that the study's findings should not be used to judge the safety of the US milk supply.

The US Food and Drug Administration still concludes that the US milk supply is safe. Its initial findings on 297 retail dairy product samples were negative for viable virus. In light of recent H5N1 outbreaks in dairy herds, federal health officials have reiterated their warnings about illness risks from drinking raw milk.

Five countries reported new polio cases this week, including Afghanistan and Pakistan, which both reported new wild poliovirus type 1 (WPV1) cases, according to the latest weekly update from the Global Polio Eradication Initiative (GPEI).

Afghanistan reported one WPV1 case, which involves a patient from Hilmand province, bringing its total for the year to five. Similarly, Pakistan reported a new WPV1 infection, in a patient from Sindh province, also boosting its total for 2024 to five cases.

The two countries are among the few where WPV1 is still endemic. The new cases in Afghanistan and Pakistan so far this year are nearly equal to the six cases each reported for all of 2023. 

Vaccine-derived cases in 3 countries

Three countries reported more vaccine-derived polio cases. The Democratic Republic of the Congo reported one infection involving circulating vaccine-derived poliovirus type 1 (cVDPV1), lifting its total for the year to four. 

Two countries reported more circulating vaccine-derived poliovirus type 2 (cVDPV2) cases, South Sudan, with one new illness, and Yemen, with three more cases. South Sudan's case—its fifth of 2024—is from Upper Nile province. Yemen has three more cases, two in Alhudaidah and one in Ibb, lifting the country's total to 10.

The Biomedical Advanced Research and Development Authority (BARDA), part of the US Department of Health and Human Services, yesterday announced up to $500 million in Project NextGen funding to plan and conduct multiple phase 2b clinical trials evaluating novel vaccines administered as a nasal spray or as a pill to protect against symptomatic COVID-19.

Assistant Secretary for Preparedness and Response Dawn O'Connell, JD, said, "The next generation vaccines that BARDA is investing in may bolster our protection against COVID-19 and be easier to administer through intranasal or oral delivery."

The project awards were made through BARDA's Rapid Response Partnership Vehicle to support the following companies in readying their vaccine candidates for phase 2b clinical trials:

• Up to $453 million to Vaxart of San Francisco for developing an oral pill vaccine candidate, adenovirus serotype 5 (Ad-5). BARDA will provide an initial $65.7 million for early trial milestones, with remaining funds provided as the effort successfully advances toward trial execution. Vaxart will execute its own Phase 2b clinical trials.
• Approximately $34 million to Castlevax, part of the Mount Sinai Health System in New York City, to develop its intranasal vaccine candidate, CVAX-01.    
• About $40 million to Cyanvac of Athens, Georgia, to advance its intranasal vaccine candidate, CVXGA. 

Castlevax and Cyanvac phase 2b trials are in partnership with BARDA's Clinical Studies Network.