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The first human case of the more severe ‘clade Ib’ mpox virus to be reported in the UK has been detected in London, the UK Health Security Agency (UKHSA) has said.
On 30 October 2024, Susan Hopkins, chief medical adviser at the UKHSA, said that the infected patient had travelled to unnamed African countries on holiday and returned to London on an overnight flight on 21 October 2024.
“They developed initial flu-like symptoms more than 24 hours later, and then, subsequently, on the 24 October, started to develop a rash, which progressed over subsequent days, and attended an emergency department in London where they were swabbed, tested and sent home to isolate whilst the results were pending,” she said.
The clade 1b strain of the virus was confirmed on 29 October 2024 by the UKHSA’s Rare and Important Pathogens Laboratory. Following the results, the patient was transferred to the Royal Free Hospital’s High Consequence Infectious Diseases Unit in London.
Despite this being the first confirmed case in the UK, Hopkins said: “We consider the risk for the general population is very low and remains so for this incident, but clearly we will be watching and determining whether there are wider contacts that we need to contact trace for those days prior to his development of a rash.
“We’re still working through the full potential of people that we may contact trace, but we are initially tracing his household contacts, and that is a number of less than ten.”
Mpox — formerly known as ‘monkeypox’ — is a virus from the same family as smallpox and presents with a rash, often beginning on the face or genital area, which may be mild and localised, but can also be severe and disseminated.
The virus spreads mainly through close contact with someone who has the virus. This includes skin-to-skin (e.g. touching or sexual intercourse), mouth-to-mouth (e.g. kissing) or face-to-face (e.g. talking or breathing close to one another). It can also be passed on via contaminated materials, animals or during pregnancy.
There are two major genetic groups (clades) of the virus: clade II mpox (formerly known as ‘West African clade’) and clade I mpox (formerly known as ‘Central African or Congo basin clade’), which is considered to be more severe.
The new clade Ib mpox virus first emerged in September 2023 in the east of the Democratic Republic of Congo. In August 2024, the World Health Organization declared a “public health emergency of international concern (PHEIC)”, following a rapid rise in the number of cases of a new clade 1 mpox strain in Africa.
In an announcement published on 30 October 2024, alongside the media briefing, the UKHSA said the agency is “working closely with the NHS and academic partners to determine the characteristics of the pathogen and further assess the risk to human health”.
Commenting on the case, Brian Ferguson, associate professor of immunology at the University of Cambridge, said: “This is an unsurprising event and likely will not be the only time this happens in the UK. It follows discovery of similar imported cases in Germany and Sweden and other countries globally.
“The close contacts of this individual are being sought and should be offered testing and vaccines in line with current policy to help reduce the chances of onward transmission.”
Wes Streeting, secretary of state for health and social care, said: “The overall risk to the UK population currently remains low and the government is working alongside [the] UKHSA and the NHS to protect the public and prevent transmission.
“This includes securing vaccines and equipping healthcare professionals with the guidance and tools they need to respond to cases safely.”
“We are also working with our international partners to support affected countries to prevent further outbreaks,” he added.
In September 2024, the UKHSA announced that the UK government had ordered 150,000 additional doses of mpox vaccine from manufacturer Bavarian Nordic in preparation for any clade I mpox cases that may enter the country. At present, vaccination is prioritised in those individuals at higher risk of contracting the disease.
Commenting on the confirmed case, Steve Russell, NHS national director for vaccination and screening, said: “The NHS is fully prepared to respond to the first confirmed case of this clade of mpox.
“Since mpox first became present in England, local services have pulled out all the stops to vaccinate those eligible, with tens of thousands in priority groups having already come forward to get protected, and while the risk of catching mpox in the UK remains low, if required the NHS has plans in place to expand the rollout of vaccines quickly in line with supply.”
