London Confirms Initial Clade Ib Mpox Case

The U.K. Health Security Agency (UKHSA) announced today that it had detected its first Clade Ib mpox human case in London, England.

As of October 30, 2024, the infected individual has been transferred to the Royal Free Hospital High Consequence Infectious Diseases unit.

This person had recently traveled to countries in Africa that are reporting Clade Ib mpox outbreaks.

The UKHSA and NHS stated that the risk to the U.K. population remains low and will not disclose further details about this case. Any contacts will be offered testing and vaccination as needed and advised on any necessary further care if they have symptoms or test positive.

This is the first detection of this Clade of mpox in the U.K. It differs from mpox Clade II, which has circulated at low levels in the U.K. since 2022.

U.K. Health and Social Care Secretary Wes Streeting commented in a press release, "The overall risk to the U.K. population currently remains low... (We) are securing vaccines and equipping healthcare professionals with the guidance and tools to respond to cases safely."

According to a recent World Health Organization analysis, Clade 1 viruses have been detected in Central Africa for decades.

In the United States, the CDC reported on October 19, 2024, that 2,230 Clade II cases were confirmed in 2024, compared with 1,096 reported in 2023.

In the U.S., Bavarian Nordic's JYNNEOS® (MVA-BN®, IMVAMUNE®, IMVANEX®) two-dose mpox/smallpox vaccine is commercially available at clinics and pharmacies. Vaccine efficacy data against Clade Ib is pending.