The government is working to head off human bird flu infections. The U.S. government has awarded Moderna $590 million to advance the development of its bird flu vaccine, as the country doubles down on efforts to tackle increasing infections in humans.

H5N1 vaccines have been previously licensed, and millions are in the national stockpile. But even with the news of the country’s first human death due to bird flu, vaccination isn’t yet recommended.

"The Chinese poultry lineage may have experienced more vaccine-driven selection compared to other lineages," the researchers wrote.