Bird Flu H5N1 Detected in Three More US States, WHO Raises Alert Level

WHO Raises H5N1 Alert as Bird Flu Spreads to Three New US States

The World Health Organization raised its H5N1 influenza alert level on Thursday, February 26, 2026, after health authorities in three additional US states — Nebraska, Wisconsin, and Virginia — confirmed new detections of the virus in both livestock and, in two cases, humans who had close contact with infected animals. The developments bring the total number of US states reporting H5N1 activity to 23, up from 14 at the start of 2026.

The two human cases — a dairy farm worker in Nebraska and a poultry processing employee in Wisconsin — were both hospitalized with severe respiratory symptoms. Neither had died as of Thursday evening. Both are being treated with antiviral medications including oseltamivir, and contact tracing operations are active around both facilities.

CDC Director Dr. Mandy Cohen said the agency was "intensifying surveillance significantly" and working with state health departments to expand testing capacity. She stressed that H5N1 does not currently spread efficiently between humans, but acknowledged that the virus's continued circulation in mammalian species increases the risk of adaptive mutations that could change that picture.

Dairy Farms at the Center

The current US outbreak has a distinctive epidemiological profile: unlike previous H5N1 waves, which spread primarily through wild bird populations and commercial poultry flocks, this wave has established persistent transmission chains in dairy cattle herds. Over 1,400 dairy operations across 23 states have now reported H5N1-positive cattle, and the virus has been detected in commercially sold milk — though pasteurization destroys the active virus.

The persistence of H5N1 in cattle is unusual and concerning because cattle provide sustained, close-contact exposure for farm workers over extended periods, rather than the episodic contact associated with poultry handling. Epidemiologists worry this increases the cumulative probability of human infection events.

According to Dr. Michael Osterholm, Director of the Center for Infectious Disease Research and Policy at the University of Minnesota, "Every additional human case is another spin of a roulette wheel. Most of the time nothing happens. But if the virus acquires the mutations needed for human-to-human transmission in an infected person, the consequences could be catastrophic and rapid."

US and WHO Response

WHO's raised alert level does not constitute a public health emergency of international concern — the organization's highest designation — but it signals that member states should accelerate preparedness planning, including review of vaccine stockpiles and antiviral reserves. The organization has urged countries with significant poultry and cattle operations to intensify animal surveillance.

The US government has contracted for 10 million doses of a candidate H5N1 vaccine for humans, though the vaccine is not licensed for mass public use. The Department of Health and Human Services said it could invoke emergency use authorization "within weeks" of a determination that human-to-human transmission had occurred.

The Biden-era emergency stockpile of antivirals — assembled after the 2009 H1N1 pandemic — remains largely intact, but public health officials warn that the supply chain for personal protective equipment in agricultural settings is inadequate. Whether the US agricultural sector, the federal government, and international health agencies can coordinate fast enough to contain an accelerating outbreak is a question no one wants to have to answer under pressure.