The US Department of Agriculture (USDA) will spend $502 million to ensure its rapid response to any future avian influenza cases as the country's worst-ever outbreak of the virus levels off, Reuters reported, citing the agency on Friday.

Avian influenza has killed 58.7 million chickens, turkeys, and other birds across 47 states since January 2022, a record number in the US, according to June 7 data from the Centers for Disease Control and Prevention.

There have been no new cases in commercial poultry flocks since April 19, 2023, or in backyard flocks since May 18, 2023, USDA said.

The new funding will allow USDA's Animal and Plant Health Inspection Service (APHIS) to prepare for the possibility of future outbreaks as the virus continues to spread in other countries, USDA said.

The agency has already spent $793 million on its response to the outbreak, including disposing of dead birds, implementing quarantines, and conducting surveillance.

The USDA is also testing avian influenza vaccines, Reuters reported in April.