The Government has ordered more than 150,000 doses of mpox vaccine in preparation for the “likely” discovery of cases of a new infectious strain in the UK.
The jab developed by Bavarian Nordic will be offered to eligible groups as part of efforts to protect the population against Clade 1b mpox before it is detected in the UK.
Experts have said the new strain is associated with a more severe disease and higher mortality rates than the one that caused the global mpox outbreak in 2022.
No cases of Clade Ib mpox have been recorded in the UK, but infections have been confirmed in Sweden and Thailand.
The UK Health Security Agency (UKHSA) has repeatedly said the risk to the general population remains low.
Gay, bisexual, or other men who have sex with men will be offered the vaccine, as well as healthcare workers in infectious disease inpatient units and sexual health services.
Health Secretary Wes Streeting said: “No cases of clade 1 mpox have been detected in the UK, but we are taking steps to ensure the country is prepared with a robust vaccination programme that protects those who may be at high risk.
“Across government, we are closely monitoring the spread of this virus overseas and are proud to be at the forefront of the international response, including through our early support to the Democratic Republic of Congo.”
Mpox is a viral infection that causes flu-like symptoms and pus-filled lesions, and while usually mild, it can kill. It spreads through close contact, including sexual contact.
Last month, the World Health Organisation declared that the outbreak of Clade I mpox in central Africa was a global health emergency.
The offshoot of the mpox virus was first identified in the Democratic Republic of Congo (DRC) but has since spread to other neighbouring countries.
In a technical briefing published by the UKHSA on Monday, the agency warned that is was “highly likely” that imported cases would occur in the UK but that they would be detected.
“The low transmissibility of the virus means that they can be controlled by isolation of cases, contact tracing, post-exposure vaccination and quarantine of contacts,” they added.
The briefing concludes that the Clade 1b form of the virus is more transmissible than the Clade 2 offshoot of the virus that caused an outbreak in the UK in 2022, which has now been contained.
“By the time cases are detected in the UK, there will be established chains of sexual transmission in country,” the briefing says.
“It is reasonable to assume that a similar-sized outbreak would occur in the UK compared to the global clade 2b outbreak with a potential increase in severity. It is likely that this would need to be managed more widely in the NHS than within infectious diseases services.”
Professor Susan Hopkins, Chief Medical Advisor at the UK Health Security Agency, said officials were preparing for potential cases of clade 1 in the UK.
“Alongside vaccination, we have been working rapidly to ensure that clinicians are aware and able to recognise cases promptly, that rapid testing is available, and that protocols are developed for the safe clinical care of people who have the infection and the prevention of onward transmission,” she said.
