• H5N1 avian influenza cases have slowed in both animals (dairy cattle, poultry) and humans in the US, as reported by the CDC.
• Despite the decline, experts emphasize the need for continued monitoring and surveillance due to the potential for resurgence or mutation of the virus.
• Concerns remain regarding the virus's spread in animals, the possibility of human-to-human transmission, and the effectiveness of current surveillance and testing efforts.

Recent data indicates a slowdown in H5N1 bird flu cases in the United States among both animals and humans. The decline is observed in dairy cattle (since January) and poultry flocks. Since the outbreak began in 2022, there have been 70 human cases, one resulting in death. Experts caution against complacency, highlighting the potential for the virus to mutate, adapt, or resurge, which reinforces the need for continued surveillance and preparedness.

• What: Decline in H5N1 avian influenza cases among animals and humans in the U.S., alongside persistent concerns about future outbreaks and mutations.
• Who: CDC, USDA, state and local health departments, farmers, poultry farm workers, dairy workers, public health experts (Alicia Budd, Todd Davis, James Lawler, Tony Moody, Dean Blumberg).
• When: Slowdown observed since January 2025 in dairy cattle and after February 2025 in poultry flocks. The first human case was confirmed in April 2024. The outbreak began in 2022.
• Where: United States (17 states affected in animal herds, 13 states with human cases).

The slowdown in H5N1 cases is a positive development, but experts highlight the need for caution. The virus's ability to mutate and adapt poses a continued threat. Discrepancies exist in the perceived effectiveness of current surveillance and testing efforts. Enhanced coordination between different agencies is needed to achieve a more comprehensive understanding of the situation. The potential economic impact on farmers and the food supply chain also warrants consideration.

"It's certainly great to see these declines in both animal and human cases, but it's also critical that we maintain targeted monitoring and our general surveillance, so that if this situation changes, we'd be able to identify that quickly."

"I think that the problem we have right now is that we have an incomplete view because testing of animals falls under one department, testing of people falls under a different department. They don't necessarily communicate in real time with accurate information and, the two agencies in question here, they've got very different purposes."

"The real question," he said, "is what happens next? I doubt we will be so lucky that H5 has run its course in the U.S. and we are done with it."

While the decline in H5N1 bird flu cases offers a respite, it is essential to remain vigilant. The possibility of viral mutation, adaptation, and resurgence requires sustained monitoring and coordinated response efforts. Addressing the challenges in surveillance and testing, improving inter-agency communication, and developing effective vaccines are crucial steps in mitigating the ongoing risks associated with avian influenza.