Mpox Clade 1 Cases Deadlier than Clade 2

A new framework was recently released by the World Health Organization (WHO) that will guide health authorities, communities, and other stakeholders in preventing and controlling mpox outbreaks, eliminating human-to-human transmission of the disease, and reducing spillover of the virus from animals to humans.

Mpox is a viral illness caused by the monkeypox virus (MPXV).

There are two different clades of the MPXV: clade I and clade II. Clade I outbreaks are deadlier than clade II outbreaks. 

In the United States, clade II cases were reported to have a fatality rate of .002%.

A significant outbreak of the clade I virus in the Democratic Republic of the Congo (DRC) continues today, where cases have been detected for decades. Since the beginning of 2024, over 6,500 cases and 345 deaths have been reported in the DRC.

This data reflects a fatality rate of .05%.

As of May 26, 2024, most U.S. mpox cases continue to be in people who are not vaccinated or have only received one dose of the JYNNEOS® (MVA-BN®, IMVAMUNE®) vaccine. The U.S. CDC recommends that persons at risk for mpox exposure complete the 2-dose  vaccination.

In the U.S., the JYNNEOS vaccine is offered at clinics and pharmacies in select cities.