Health officials on Saturday said they have identified the first U.S. case of an mpox strain that has recently prompted global health alerts over concerns about its spread, severity and transmissibility.

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.

The first known case of clade I mpox in the U.S. was recently discovered in a person in California, the Centers for Disease Control and Prevention said Saturday.