A new strain of mpox, formerly known as monkeypox, has been identified in an individual in England, UK health authorities confirmed.
The infection was detected in a person who had recently returned from Asia, and initial analysis shows the virus is a combination of two major mpox lineages.
Officials say they are still assessing what this new strain means for public health, but stress that viral evolution is normal. They also reiterated that vaccination remains the most effective protection against severe illness, even though many mpox cases are generally mild.
The newly detected strain contains genetic elements from both clade Ib and clade IIb. The strain has not yet been formally named.
The discovery comes as the clade Ib strain has shown early signs of local transmission in parts of Europe, while clade IIb was responsible for the widespread global mpox outbreak in 2022.
In the UK, vaccines are available to groups at higher risk of mpox, including individuals with multiple sexual partners, those who participate in group sex, and people who attend sex-on-premises venues. Health officials say the vaccine offers 75–80% protection.
Although the vaccine has not yet been tested specifically against this new strain, experts believe it will still provide a high level of protection.
Dr. Katy Sinka, head of sexually transmitted infections at UKHSA, said genomic testing made it possible to detect the new strain early. She emphasized that viral evolution is expected and that ongoing analysis will help clarify how mpox continues to change. She urged eligible individuals to get vaccinated.
Prof. Trudie Lang of the University of Oxford said the discovery underscores that mpox continues to circulate and evolve globally. She noted that while the UK has strong systems to identify and contain outbreaks, many vulnerable populations in other countries lack reliable access to vaccines and surveillance tools.
She added that if more cases of this new strain emerge in the UK or internationally, health authorities will need to determine how it spreads and whether it causes more severe illness than existing strains.
Globally, nearly 48,000 mpox cases have been confirmed so far in 2025, with about 2,500 reported in the past month—most in central Africa.
Mpox is an unpleasant illness that typically causes a rash or skin lesions lasting two to four weeks, along with symptoms such as fever, headaches, muscle pain, back pain, and fatigue.
The virus spreads through close physical contact, coughing or sneezing, or touching contaminated clothing, bedding, or towels.
Health officials advise anyone who suspects they may have mpox to contact NHS 111 for guidance.
