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New mpox variant identified in UK traveller
UK health authorities confirmed a new strain of mpox in an individual who recently returned from Asia, marking the first detection of a hybrid variant combining two major clades of the virus.
Strain composition and origins
The newly identified variant merges genetic elements from clade Ib and clade IIb, two distinct mpox strains. While clade IIb drove the 2022 global outbreak, clade Ib has shown signs of local transmission in parts of Europe this year. The hybrid strain currently has no official designation.
UK Health Security Agency (UKHSA) officials stated the discovery resulted from routine genomic surveillance but emphasized the need for further analysis to determine its potential impact.
Vaccination and protection measures
Health authorities continue to recommend vaccination for high-risk groups, including gay, bisexual, and other men who have sex with men. The existing vaccine is estimated to be 75-80% effective against severe disease, though its efficacy against this new strain remains untested.
"Vaccination remains the most reliable way to reduce severe outcomes. If you're eligible, ensure you've received the jab," urged Dr. Katy Sinka, UKHSA's head of sexually transmitted infections.
Global context and expert concerns
Nearly 48,000 mpox cases have been confirmed globally in 2025, with 2,500 reported in the past month-primarily in Central Africa. Experts warn that unchecked transmission increases the risk of viral recombination and adaptation.
"The more the virus circulates, the more opportunities it has to evolve into a persistent human pathogen," said Dr. Boghuma Titanji, assistant professor of medicine at Emory University.
Professor Trudie Lang of the University of Oxford highlighted the UK's robust detection systems but cautioned that vulnerable populations in other regions face greater challenges due to limited vaccine access.
Symptoms and transmission
Mpox typically causes a rash lasting 2-4 weeks, accompanied by fever, headaches, muscle aches, and fatigue. The virus spreads through close physical contact, respiratory droplets, or contaminated materials like bedding or clothing.
UKHSA advises anyone exhibiting symptoms to contact NHS 111 for guidance. Officials are monitoring the situation closely to assess the strain's transmissibility and severity compared to previous variants.
