President Trump’s decision to pull out of the international health agency could deprive the United States of crucial scientific data and lessen the country’s influence...

Officials have discovered the virus in 645 herds of dairy cattle, more than in any other state so far.

Even as the H5N1 virus evolves, gaps remain in the nation’s contingency plans for human testing, scientists say.

Hoau-Yan Wang, a professor at City College, published studies supporting simufilam, now in advanced clinical trials.

As the virus continues to mutate, scientific advisers to the C.D.C. are urging Americans to roll up their sleeves again for annual vaccinations.

There is no guarantee that a person-to-person virus would be benign, scientists say, and vaccines and treatments at hand may not be sufficient.

The worker had respiratory symptoms, unlike the first two. But the risk to the public remains low, federal health officials said.

A single spillover, from a bird to a cow, led to the infections, a review of genetic data has found.

Americans with Covid or other respiratory infections may return to daily activities if they don’t have a fever and their symptoms are improving.

The pandemic and recent wildfires have shown how unhealthy indoor air can be. But scientific and governmental inertia have slowed the necessary remedies.