Health officials have identified a new strain of mpox in England after a person who recently travelled to Asia was tested for the virus.
Genome sequencing showed that the virus was a “recombinant” form containing elements of two types of mpox currently in circulation: the more severe clade 1, and the less virulent clade 2, which sparked the 2022 global mpox outbreak.
The UK Health Security Agency said on Monday it was continuing to “assess the significance of the strain”. While most mpox infections are mild, officials urged people who are eligible to get vaccinated to protect themselves.
“It’s normal for viruses to evolve, and further analysis will help us understand more about how mpox is changing,” said Dr Katy Sinka, the head of sexually transmitted infections at UKHSA.
Mpox, formerly known as monkeypox, is a viral infection related to smallpox. It can be passed on through close physical contact with mpox blisters or scabs, through touching contaminated material such as clothing, bedding or towels, or through infected people’s coughs and sneezes. It can also be caught from infected animals, such as rats, mice and squirrels.
Symptoms can take three weeks to appear and include a high temperature, a headache, muscle pain and exhaustion. A rash typically appears within days of the first symptoms.
The UKHSA said the recombinant strain was “not unexpected” as both clades are circulating, adding that its emergence highlighted the potential for the virus to continue evolving and the importance of ongoing genomic surveillance.
The World Health Organization (WHO) declared a year-long public health emergency during the mpox outbreak in 2022. A second public emergency was declared in 2024 when another mpox epidemic broke out, largely affecting the Democratic Republic of the Congo. That emergency was declared over in September this year.
Figures for 2025, which run to the end of October, show that the WHO recorded nearly 48,000 confirmed mpox cases worldwide, including 201 deaths, in 94 countries.
The UK has an 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.
Trudie Lang, professor of global health research at the University of Oxford, said: “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.”
