The UK Health Security Agency (UKHSA) has announced that it has detected a further two cases of Clade Ib mpox. The two new cases are both household contacts of the first case, announced on 30 October. This brings the total number of confirmed UK cases to three.
These are the first detected cases 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). Contacts of all three 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.
The UKHSA, NHS and partner organisations have well-tested capabilities to detect, contain and treat novel infectious diseases. There has been extensive planning underway to ensure healthcare professionals are equipped and prepared to respond to any confirmed cases.
The first 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. The further two 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.
The 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, it will continue to monitor and learn more about the severity, transmission and control measures. UKHSA will initially manage Clade Ib as a high consequence infectious disease (HCID) whilst it learns 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.”
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.
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.
The UKHSA has published its first technical briefing on clade I mpox which provides further information on the current situation and UK preparedness and response.