Latest update on Clade Ib mpox

Latest update

UKHSA is aware of small numbers of locally-acquired cases of clade Ib mpox in the USA, Spain, Italy, the Netherlands and Portugal which have no connection to countries with known clade Ib mpox transmission.  

This suggests there is now community transmission of clade Ib mpox globally. Most of the new cases identified in Europe and the USA have been in gay, bisexual and other men who have sex with men, a population in which clade Ib mpox transmission has not previously been observed.  

Mpox is usually a mild infection, and clade Ia and Ib mpox are no longer classified as a high-consequence infectious disease (HCID). However, it can be severe in some cases. 

The UK has a routine mpox vaccination programme in place for eligible groups, including those who:  

• have multiple sexual partners  
• have group sex  
• visit sex-on-premises venues  

Studies show that the vaccine is around 75 to 80% effective in protecting people against clade II mpox. Although there are no studies on vaccine effectiveness against clade Ib mpox, vaccine protection is expected. A high proportion of people in eligible groups in the UK have already had the vaccine.  

To check if you are eligible or to book an appointment, visit Mpox vaccine - NHS.   

Common symptoms of mpox include a skin rash or pus-filled lesions which can last 2 to 4 weeks. It can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.  

Dr Katy Sinka, Head of Sexually Transmitted Infections at UKHSA:  

The ways in which we are seeing mpox continue to spread globally is a reminder to come forward for the vaccine, if you are eligible.  

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.  

It is important to remain alert to the risks from this unpleasant illness. Anyone who thinks they may have mpox should contact NHS 111 for advice on what to do.

UKHSA has robust mechanisms in place to investigate suspected cases of mpox of all clade types, irrespective of travel history, with regular updates on confirmed UK cases of mpox.  

UKHSA has today published a technical assessment on mpox to reflect the latest epidemiology. 

Further information about symptoms is available on the NHS website.  

Dr Will Nutland, Director at The Love Tank said:  

Mpox hasn’t been making headlines for more than a year but these cases show that mpox has not gone away. Routine availability of mpox vaccination, through NHS sexual health clinics, provides an effective way of protecting against mpox. The Love Tank continues to work alongside NHS colleagues to ensure that vaccination programmes continue to reach those who most need them, including in community settings.

Prof. Matt Phillips, President of the British Association for Sexual Health and HIV said:  

We encourage anyone who is eligible for the vaccine against mpox to talk to their local sexual health clinic and arrange to be vaccinated.   

These cases are a reminder both that mpox has not gone away, and of the importance of vaccine programmes in reducing the impact of mpox infection.

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.

Previous

07 April 2025

The UK Health Security Agency (UKHSA) has detected a single confirmed human case of Clade Ib mpox where the case had no reported travel history and no reported link with previously confirmed cases in the UK.

More work is ongoing to determine where the individual, who is resident in the North East of England, may have caught the infection.

The individual was diagnosed in March, all contacts have been followed up and no further cases identified. The risk to the UK population remains low. Clade Ia and Ib mpox are no longer classified as a high consequence infectious disease (HCID).

UKHSA has robust mechanisms in place to investigate suspected cases of mpox of all clade types, irrespective of travel history.  

All previous cases in the UK to date have either travelled to an affected country or have a link to someone that has.

Common symptoms of mpox include a skin rash or pus-filled lesions which can last 2 to 4 weeks. It can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.

Further information about symptoms is available on the NHS website.

UKHSA Mpox Incident Director Dr Gillian Armstrong said:

The risk to the UK population from mpox remains low.

The majority of people who have presented with symptoms report close physical contact, including massages, or sex prior to developing symptoms.

Regardless of whether you have travelled or not, it is important to remain alert to the risks. Anyone who thinks they may have mpox should contact NHS 111 for advice on what to do.

While mpox infection is mild for many, it can be severe for some and UKHSA is committed to preventing its spread within the UK.

Previous

19 March 2025

Clade I mpox no longer considered a high consequence infectious disease

Clade Ia and Ib mpox will no longer be classified as a high consequence infectious disease (HCID) following a review of available evidence by the Advisory Committee on Dangerous Pathogens, the UK Health Security Agency has confirmed today.

This decision has been taken because the evidence related to this clade no longer meets the criteria for an HCID, which includes having a high mortality rate and a lack of available interventions.

However, the decision should not be interpreted as clade I mpox no longer being of any public health consequence. The disease is still a public health emergency of international concern as defined by the WHO.

Sexual and close physical contact is the main way that mpox spreads.

There have been no reported deaths from mpox in the UK to date, and vaccination is available for higher risk contacts, healthcare workers, and those who are most at risk.

Emma Richards, Incident Director at the UK Health Security Agency, said:

There is now firm evidence of vaccine effectiveness and a low mortality rate for cases of clade I mpox, alongside heightened clinical awareness of symptoms, and access to rapid diagnostic testing and safe therapies with emerging evidence of efficacy.

This change does not alter our overall public health response and we remain committed to preventing the spread of clade I mpox within the UK.

While mpox infection is mild for many, it can cause severe symptoms including unusual rashes and blisters, a fever and headache.

The majority of people who have presented with symptoms report close physical contact, including massages, or sex prior to developing symptoms. It’s important people who have travelled to affected countries in Africa remain alert to the risks and seek medical advice if necessary.

All 4 UK Chief Medical Officers have agreed to accept the recommendation.

There have been no cases of clade Ia mpox in the UK, and only a small number of cases of clade Ib mpox. Most of these cases have appeared in returning travellers from affected areas in Africa with the others being household contacts of a case.

There has been no community transmission of clade I mpox within the UK and the risk to the population remains low.

In the context of the outbreak in parts of Africa, we expect to see the occasional imported case of clade Ib mpox in the UK.

13 February 2025

A new case of clade Ib mpox has been detected in England, the UK Health Security Agency (UKHSA) can confirm. 

The case was detected in London and the individual is now under specialist care at the Royal Free Hospital High Consequence Infectious Diseases unit. They had recently returned from Uganda, where there is currently community transmission of clade Ib mpox. The UKHSA and NHS will not be disclosing any further details about the individual.

The risk to the UK population remains low. In the context of the outbreak in parts of Africa, we expect to see the occasional imported case of clade Ib mpox in the UK.

This is the eighth case of clade Ib mpox confirmed in England since October 2024. This case has no links to the previous cases identified in England.

Close contacts of the case are being followed up by UKHSA and partner organisations. Contacts will be offered testing and vaccination where needed to prevent further infections and they will be advised on any necessary further care if they have symptoms or test positive.

Dr Merav Kliner, Incident Director at UKHSA, said:

The risk to the UK population remains low. Close contacts have been identified and offered appropriate advice in order to reduce the chance of further spread.

Clade Ib mpox has been circulating in several countries in Africa in recent months. Imported cases have been detected in a number of countries including Belgium, Canada, France, Germany, Sweden and the United States.

There has been extensive planning undertaken to ensure healthcare professionals are equipped and prepared to respond to confirmed cases.

Further updates on clade Ib mpox case numbers will be published on the following page: Confirmed cases of mpox clade Ib in United Kingdom.

Previous

27 January 2025

Another case of clade Ib mpox has been detected, bringing the total number of confirmed cases since October 2024 to 7, the UK Health Security Agency (UKHSA) can confirm.

The individual had recently travelled to Uganda. The risk to the UK population remains low.

The UKHSA and NHS will not be disclosing any further details about the individual.

Professor Susan Hopkins, Chief Medical Adviser at UKHSA, said:

The risk to the UK population remains low. Close contacts have been identified and offered appropriate advice in order to reduce the chance of further spread.

20 January 2025

A new case of clade Ib mpox has been detected in England, the UK Health Security Agency (UKHSA) can confirm.  

The case was detected in East Sussex and the individual is now under specialist care at Guy’s and St Thomas’ NHS Foundation Trust. They had recently returned from Uganda, where there is currently community transmission of clade Ib mpox. The UKHSA and NHS will not be disclosing any further details about the individual. 

The risk to the UK population remains low. In the context of the outbreak in parts of Africa, we expect to see the occasional imported case of clade Ib mpox in the UK. 

This is the sixth case of clade Ib mpox confirmed in England since October 2024. This case has no links to the previous cases identified in England.

Close contacts of the case are being followed up by UKHSA and partner organisations. Contacts will be offered testing and vaccination where needed to prevent further infections and they will be advised on any necessary further care if they have symptoms or test positive. 

Dr Meera Chand, Deputy Director at UKHSA, said: 

It is thanks to clinicians rapidly recognising the symptoms and the work of our specialist laboratory that we have been able to detect this new case.

The risk to the UK population remains low following this sixth case, and we are working rapidly to trace close contacts and reduce the risk of any potential spread.

Clade Ib mpox has been circulating in several countries in Africa in recent months. Imported cases have been detected in a number of countries including Belgium, Canada, France, Germany, Sweden and the United States. 

There has been extensive planning undertaken to ensure healthcare professionals are equipped and prepared to respond to any further confirmed cases.

29 November 2024

A new case of clade Ib mpox has been detected in England, the UK Health Security Agency (UKHSA) can confirm.  

The case was detected in Leeds and the individual is now under specialist care at Sheffield Teaching Hospitals NHS Foundation Trust. They had recently returned from Uganda, which is seeing community transmission of clade Ib mpox. The UKHSA and NHS will not be disclosing any further details about the individual. 

The risk to the UK population remains low. We expect to see the occasional imported case of clade Ib mpox in the UK. 

This is the fifth case of clade Ib mpox confirmed in England in recent weeks. This case has no links to the previous cases identified. All 4 previous cases were from the same household and all have now fully recovered.  

Close contacts of the case are being followed up by UKHSA and partner organisations. Any contacts will be offered testing and vaccination as needed and advised on any necessary further care if they have symptoms or test positive. 

Professor Susan Hopkins, Chief Medical Adviser at UKHSA, said: 

It is thanks to clinicians rapidly recognising the symptoms and our diagnostics tests that we have been able to detect this new case. 

The risk to the UK population remains low following this fifth case, and we are working rapidly to trace close contacts and reduce the risk of any potential spread. In accordance with established protocols, investigations are underway to learn how the individual acquired the infection and to assess whether there are any further associated cases. 

Clade Ib mpox has been widely circulating in the Democratic Republic of Congo (DRC), Burundi, Rwanda, Uganda and Kenya in recent months. Imported cases have been detected in Canada, Sweden, India, Thailand and Germany. 

There has been extensive planning underway to ensure healthcare professionals are equipped and prepared to respond to any further confirmed cases.

6 November 2024

One further case of clade Ib mpox has been detected in a household contact of the first case, the UK Health Security Agency (UKSHA) can confirm.  

This brings the total number of confirmed cases to 4, all of which belong to the same household. 

The patient is currently under specialist care at Guy’s and St Thomas’ NHS Foundation Trust in London. The risk to the UK population remains low. 

The patient has been isolating since identified as a contact of the first case and no additional contact tracing is required. 

Professor Susan Hopkins, Chief Medical Adviser at UKHSA, said: 

Mpox is very infectious in households with close contact and so it is not unexpected to see further cases within the same household. 

The overall risk to the UK population remains low. We are working with partners to make sure all contacts of the cases are identified and contacted to reduce the risk of further spread.

Contacts of cases are being followed up by UKHSA and partner organisations. All contacts will be offered testing and vaccination as needed and advised on any necessary further care if they have symptoms or test positive. 

There has been extensive planning underway to ensure healthcare professionals are equipped and prepared to respond to any further confirmed cases.

4 November 2024

Two cases of clade Ib mpox have been detected in household contacts of the first case, the UK Health Security Agency (UKSHA) can confirm. This brings the total number of confirmed cases to 3.

The 2 patients are currently under specialist care at Guy’s and St Thomas’ NHS Foundation Trust in London. The risk to the UK population remains low.

There has been extensive planning underway to ensure healthcare professionals are equipped and prepared to respond to any further confirmed cases.

Professor Susan Hopkins, Chief Medical Adviser at UKHSA, said:

Mpox is very infectious in households with close contact and so it is not unexpected to see further cases within the same household.

The overall risk to the UK population remains low. We are working with partners to make sure all contacts of the cases are identified and contacted to reduce the risk of further spread.

Contacts of all 3 cases are being followed up by UKHSA and partner organisations. All contacts will be offered testing and vaccination as needed and advised on any necessary further care if they have symptoms or test positive.

30 October 2024

The UK Health Security Agency (UKHSA) has detected a single confirmed human case of clade Ib mpox. The risk to the UK population remains low.

This is the first detection of this clade of mpox in the UK. It is different from mpox clade II that has been circulating at low levels in the UK since 2022, primarily among gay, bisexual and other men-who-have-sex-with-men (GBMSM).

UKHSA, the NHS and partner organisations have well tested capabilities to detect, contain and treat novel infectious diseases, and while this is the first confirmed case of mpox clade Ib in the UK, there has been extensive planning underway to ensure healthcare professionals are equipped and prepared to respond to any confirmed cases.

The case was detected in London and the individual has been transferred to the Royal Free Hospital High Consequence Infectious Diseases unit. They had recently travelled to countries in Africa that are seeing community cases of clade Ib mpox. The UKHSA and NHS will not be disclosing any further details about the individual.

Close contacts of the case are being followed up by UKHSA and partner organisations. Any contacts will be offered testing and vaccination as needed and advised on any necessary further care if they have symptoms or test positive.

UKHSA is working closely with the NHS and academic partners to determine the characteristics of the pathogen and further assess the risk to human health. While the existing evidence suggests mpox clade Ib causes more severe disease than clade II, we will continue to monitor and learn more about the severity, transmission and control measures. We will initially manage clade Ib as a high consequence infectious disease (HCID) whilst we are learning more about the virus.

Professor Susan Hopkins, Chief Medical Adviser at UKHSA, said:

It is thanks to our surveillance that we have been able to detect this virus. This is the first time we have detected this clade of mpox in the UK, though other cases have been confirmed abroad.

The risk to the UK population remains low, and we are working rapidly to trace close contacts and reduce the risk of any potential spread. In accordance with established protocols, investigations are underway to learn how the individual acquired the infection and to assess whether there are any further associated cases.

Health and Social Care Secretary Wes Streeting, said:

I am extremely grateful to the healthcare professionals who are carrying out incredible work to support and care for the patient affected.

The overall risk to the UK population currently remains low and the government is working alongside 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.

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 roll out of vaccines quickly in line with supply.

Clade Ib mpox has been widely circulating in the Democratic Republic of Congo (DRC) in recent months and there have been cases reported in Burundi, Rwanda, Uganda, Kenya, Sweden, India and Germany.

Clade Ib mpox was detected by UKHSA using polymerase chain reaction (PCR) testing.

Common symptoms of mpox include a skin rash or pus-filled lesions which can last 2 to 4 weeks. It can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.

The infection can be passed on through close person-to-person contact with someone who has the infection or with infected animals and through contact with contaminated materials. Anyone with symptoms should continue to avoid contact with other people while symptoms persist.

The UK has an existing stock of mpox vaccines and last month announced further vaccines are being procured to support a routine immunisation programme to provide additional resilience in the UK. This is in line with more recent independent JCVI advice.

Working alongside international partners, UKHSA has been monitoring clade Ib mpox closely since the outbreak in DRC first emerged, publishing regular risk assessment updates.

The wider risk to the UK population remains low.

UKHSA has published its first technical briefing on clade I mpox which provides further information on the current situation and UK preparedness and response.