New Mpox Variant Identified in England

The UK Health Security Agency (UKHSA) has identified a new recombinant strain of the mpox virus in an individual in England who had recently traveled to Asia.

The UKHSA says genomic sequencing revealed that the mpox genome contains elements from both clade Ib and clade IIb.

This discovery is not unexpected, as both clades are currently circulating in England.

However, this finding underscores the ongoing potential for the mpox virus to evolve and highlights the importance of continued genomic surveillance.

Dr. Katy Sinka, Head of Sexually Transmitted Infections at UKHSA, stated in a press release on December 8, 2025, "Our genomic testing has enabled us to detect this new mpox strain. It's normal for viruses to evolve, and further analysis will help us better understand how mpox is changing."

"Although mpox infection is mild for many, it can be severe. Getting vaccinated is a proven effective way to protect yourself against severe disease, so please make sure to get the jab if you are eligible."

"It is essential to remain alert to the risks from this unpleasant illness."

"Anyone who thinks they may have mpox should contact NHS 111 for advice on what to do."

According to recent data, mpox cases in England continue to be reported for both clades.

The UK has a routine mpox vaccination programme in place for eligible groups, including those who have multiple sexual partners, participate in group sex, or visit sex-on-premises venues. Studies show the vaccine is around 75% to 80% effective in protecting against mpox.  

UKHSA has shared its findings with relevant international partners, including the World Health Organization (WHO), to support global monitoring efforts.

So far in 2025, the WHO has reported over 47,000 mpox cases.

On December 5, 2025, the WHO issued a new alert about the broader transmission of the clade 1b mpox virus in several non-endemic countries, including the United States. 

The WHO's Disease Outbreak News wrote, 'Men who have sex with men with new and/or multiple partners remain at increased risk of clade Ib and also IIb MPXV infection.'

And the WHO assesses the public health risk posed by clade Ib MPXV to men who have sex with men as moderate and the risk to the general population as low in most countries.'

In the USA and other countries, the JYNNEOS® (MVA-BN®, IMVAMUNE®) vaccine is available commercially at clinics and pharmacies.