UK Health Officials Warn of Global Spread of Deadlier Mpox Strain as Cases Rise Across Europe and the US

UK health chiefs have issued an urgent warning after detecting a more dangerous strain of mpox spreading across Europe and the United States. The clade 1b variant — responsible for a wave of miscarriages and a fatality rate of up to 1% in parts of Africa — is now appearing in countries with no known travel links to regions where the strain is circulating, raising fears of wider undetected transmission.

The UK Health Security Agency (UKHSA) confirmed small numbers of clade 1b cases in Spain, Italy, the Netherlands, Portugal, and the US. Crucially, investigators say none of these patients recently visited countries with active clade 1b outbreaks, a pattern suggesting the virus may already be moving silently through sexual networks across multiple nations.

Most of the recent European cases have been identified in gay and bisexual men — a demographic that clade 1b had not previously been associated with — prompting renewed calls for vaccination among high-risk groups.

Urgent Vaccine Appeal

Dr. Katy Sinka, Head of Sexually Transmitted Infections at UKHSA, urged all eligible individuals to get vaccinated as soon as possible.

“Although mpox infection is mild for many, it can be severe.
Getting vaccinated is a proven, effective way to protect yourself against severe disease.”

UK officials emphasized that awareness and swift vaccination were key factors that helped suppress the 2022 global mpox outbreak, which was driven by the less severe clade II strain. During that outbreak, nearly 4,000 cases were recorded in the UK, and more than 68,000 people were vaccinated using the smallpox vaccine, which offers cross-protection.

A More Dangerous Strain

Clade 1b — first identified last year — has fueled a major outbreak across Central Africa, infecting tens of thousands. Countries such as the Democratic Republic of Congo have been hit especially hard, with cases also appearing in Rwanda, Uganda, Burundi and Kenya.

While the variant’s fatality rate in Africa has reached up to 1%, experts stress that this level of severity is unlikely in nations with stronger healthcare infrastructure, faster diagnosis, and better access to supportive treatment.

Spread Across Europe Raises Red Flags

Since October 2024, the UK has reported 16 clade 1b cases, all linked to recent travel. But elsewhere in Europe, signs of local spread are emerging:

• Spain reported its first locally acquired cases in early January.

• Four more cases were detected in Italy, Portugal, and the Netherlands, all in men with no travel history.

• The European Centre for Disease Prevention and Control (ECDC) says these infections likely indicate sexual-network transmission among men who have sex with men (MSM).

So far, all five European patients experienced only mild symptoms.

Global Health Officials on Alert

The World Health Organization has already declared the clade 1b outbreak in Central Africa a Public Health Emergency of International Concern — the same designation used in early 2020 for COVID-19.

Although current mpox vaccines have not yet been formally tested against clade 1b, experts believe they will still offer significant protection.

The WHO and the NHS recommend vaccination:

• Within 4 days of contact with a confirmed case

• Up to 14 days if symptoms have not appeared

• For healthcare workers and MSM even without known exposure

Symptoms and Treatment

Mpox typically causes:

• Lumpy, painful skin lesions

• Fever and chills

• Exhaustion

• Muscle aches

In rare cases, the virus can spread to the lungs or bloodstream, becoming life-threatening. There is currently no specific antiviral treatment for mpox; care focuses on supporting the immune system while the infection runs its course.

Community Response

Richard Angell, Chief Executive of the Terrence Higgins Trust, reminded the public of the painful lessons from 2022:

“The last outbreak hit gay and bisexual men incredibly hard.
While mpox is described as ‘mild,’ anyone who has had lesions on sensitive areas knows how painful and distressing it can be.”

He stressed that the UK is in a stronger position today, with a government-funded vaccine program already in place for those at highest risk.