The UK Health Security Agency (UKHSA) has confirmed the first UK case of the more serious mpox virus “clade‑1b” strain
The UK has recorded its first confirmed case of mpox caused by the clade‑1b strain, a WHO-linked variant known for severe outbreaks in Africa and parts of Europe. With no known link to previous cases, the UKHSA warns of potential community transmission. Public health officials urge close contacts to seek testing and vaccination, and remind the public to remain alert for symptoms such as fever, rash, or swollen lymph nodes.
Mpox clade 1b identified in the UK
Mpox, also known as monkeypox, is an infection that causes a rash and flu-like symptoms. There are two types of mpox, called Clade 1 and Clade 2. Clade 1 is most commonly found in parts of central and east Africa, and Clade 2 mpox is detected at low levels in many countries worldwide. In the UK, most people catch mpox infrequently.
The UK Health Security Agency (UKHSA) has identified a new recombinant mpox virus in England in an individual with a recent travel history to Asia.
Genomic sequencing revealed that the mpox genome contained elements of clades 1b and 2b.
UKHSA continues to assess the significance of the strain
Dr Katy Sinka, Head of Sexually Transmitted Infections at UKHSA, said: “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.
Remaining alert to the risks of mpox is important. Individuals who think they may have mpox should contact NHS 111 for advice on next steps.”
In the UK, a routine mpox vaccination programme is in place for eligible groups, and the vaccine has been shown to be effective at approximately 75%-80% in preventing mpox.
First cases reported in October 2025
In October 2025, the UKHSA was made aware of several locally acquired cases of clade Ib mpox in the USA, Spain, Italy, the Netherlands, and Portugal. These cases had no connection to countries with known clade Ib mpox transmission prior to the UK’s confirmed case.
Dr Katy Sinka, Head of Sexually Transmitted Infections at UKHSA: “The ways in which we are seeing mpox continue to spread globally are a reminder to come forward for the vaccine, if you are eligible.
Although mpox infection is mild for many, it can be severe.”
Richard Angell OBE, Chief Executive, Terrence Higgins Trust, said: “The last outbreak of mpox hit the gay, bi and other men who have sex with men community disproportionately hard. While it is described as ‘mild’, those who have the mpox rash around their face and body, including in intimate and sensitive areas, will tell you how unpleasant and painful it is.
In 2022, we were not prepared for the MPOX outbreak, and the tools available were hard to mobilise – this time we have a government-funded vaccine programme available to gay and bi men, and it is strongly encouraged for those who have multiple partners, take part in sex parties or visit sex on premises venues.
With Winter Pride season soon upon us across Europe, those travelling to these events would be wise to get vaccinated, at least once, if not twice. Those who have had 2 mpox jabs should have protection. Anyone experiencing a rash after sex should seek out a sexual health clinic or call THT Direct on 0808 802 1221.”
