The first case in the U.S. of a more severe strain of mpox was reported in San Mateo County, the California Department of Public Health said.

There is no evidence that the strain is spreading in California or the U.S., and the risk of contracting Clade I mpox in the U.S. remains low.

San Mateo County health officials said on Saturday they have reported the first known case of clade I mpox in California and the United States.