December 8, 2025

expert reaction to UKHSA announcement of a new mpox strain identified in England

Scientists comment on a UK Health Security Agency (UKHSA) announcement that a new mpox strain has been identified in England. 

Prof Trudie Lang, Director of the Global Health Network, University of Oxford, said:

It is of concern that there is an mpox case in the UK, and of further concern that it is a new recombinant mpox virus. This case highlights that mpox is circulating globally and is evolving, as predictable with these viruses. The recent experience we have had, and still persists in Africa, when clade Ib emerged, showed that this virus can cause severe disease, and so measures to reduce transmission and prevent spread are vital. In the UK we have excellent systems to identify cases, control onward infection, and implement vaccination campaigns as needed, and these measures should rapidly control this situation in the UK. Elsewhere in the world, in more vulnerable populations and where case detection and access to vaccinations is not so assured, this is harder to achieve. In terms of what we know about this recombinant, we will need to learn more about the nature and presentation of the infection to understand whether the disease characteristics have changed with this new recombinant. With clade Ib we observed changes in transmission, seeing person-to-person close contact as well as sexual transmission, changing from previous strains being limited mainly to animal-to-human and within households, and the previous European outbreak where the transmission was limited to close sexual transmission. So, if further cases of this strain appear in the UK, and anywhere in the world, it will be important to understand the route of transmission, the presentation and severity of disease, so we can assess whether this strain is more or less dangerous than previous ones and response accordingly with a connected global effort. 

Dr Boghuma Titanji, Assistant Professor of Medicine, Emory University, said:

“The identification of a recombinant mpox strain containing elements of both Clade I and Clade II is precisely what experts in the field feared would happen if the virus continued to spread globally without a decisive response to stop it. Orthopoxviruses are well known for their ability to exchange portions of their genome and recombine to generate new variants, this is a core mechanism of their evolution. The key concern now is whether events like this will alter the virus’s transmissibility or virulence. There are also implications for how well existing testing platforms can identify these emerging recombinant strains. The more mpox circulation we permit, the more opportunities the virus has to recombine and adapt, further entrenching mpox virus as a human pathogen that is not going away.”

Declared interests

Dr Boghuma Titanji: I have no conflicts of interest.

Prof Trudie Lang: No conflict of interest.