Clade I has historically caused more severe illness compared to clade II, the strain associated with other U.S. cases of mpox. California public health officials said recent infections indicate ...

While this the first case of clade I to be announced in the U.S., 3,004 cases of mpox clade II have been recorded since Jan. 1, 2024, according to CDC data.

By comparison, clade II outbreaks in Africa have generally had a mortality rate of around 1%, and just 0.2% of cases linked to the 2022 global outbreak were fatal.

In August 2024, the World Health Organization declared a second "Public Health Emergency of International Concern" for mpox.

Clade Ib is new and concerning, but the current situation is compounded by multiple overlapping outbreaks. “We are not dealing with one outbreak of one clade; ...

The U.S. Department of Health and Human Services said in a statement that people who have received both doses of the mpox vaccine — along with people who have already had clade II mpox — “are expected ...

Clade II mpox has been circulating in the United States since a large outbreak in 2022 and 2023. A more recent outbreak in Africa is driven by clade I, which is known to cause more severe disease.

Clade 1b, a new variant of the Clade 1 strain, is the virus that is currently spreading across Africa, and is thought to cause more severe disease than previous variants.

Clade II — Clade II is less severe. It fueled the 2022 global outbreak, according to the Miami Herald, which led to more than 32,000 infections in the U.S. What do we know about mpox clade 1b?

Clade Ib spread has been associated with men who have sex with men as well, but also sex workers and their clients, and household contacts of these individuals.

Clade II of the mpox virus causes less severe disease and has a lower mortality rate, estimated to be about 0.1%, according to the CDC. It is endemic in the western African countries of Nigeria, ...

Clade 1b infections in areas that have previously not reported mpox are spreading sexually in female sex workers and their male customers, as well as men who have sex with men, officials say.