Mpox outbreak: epidemiological overview, 12 December 2024
Updated 12 December 2024
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This report contains the latest information on mpox clade IIb cases in the UK, which have been regularly reported since May 2022. This report does not contain information relating to the clade I mpox outbreak which is predominantly occurring overseas, please see latest update on cases of clade Ib mpox.
This epidemiological overview provides an update to the number of confirmed and highly probable mpox clade IIb cases in England, Northern Ireland, Scotland and Wales since the outbreak was recognised in May 2022. Clade Ib cases are not included in these figures.
Mpox is a zoonotic infection, caused by the monkeypox virus, that occurs mostly in West and Central Africa. Prior to 2022, cases diagnosed in the UK had been either imported from countries where mpox is endemic or in contacts with documented epidemiological links to imported cases. Between 2018 and 2021, there had been 7 cases of mpox in the UK. Of these, 4 were imported, 2 were cases in household contacts, and one was a case in a health care worker involved in the care of an imported case. There was no documented community transmission in previous outbreaks.
Current epidemiological situation of mpox clade IIb up to 30 November 2024
Detection of cases of mpox clade IIb infection, acquired within the UK, were confirmed in England from 6 May 2022. The outbreak has mainly been in gay, bisexual, and other men who have sex with men without documented history of travel to endemic countries.
Suspected mpox samples that are positive using a mpox polymerase chain reaction (PCR) test are classified as confirmed cases. Samples which are positive using an orthopox PCR test are classified as highly probable cases. Orthopox is the group of viruses which includes mpox. The counts below combine both of these categories. Clade typing is conducted on confirmed mpox cases at UKHSA’s Rare and Imported Pathogens Laboratory.
Up to 31 December 2022, there were 3,732 confirmed and highly probable mpox clade IIb cases reported in the UK. Of these, 3,553 were in England, 34 were in Northern Ireland, 97 were in Scotland and 48 were in Wales.
In 2023 and 2024 (up to 30 November 2024), there have been a total of 409 cases of mpox clade IIb reported in the UK. Of these, 384 were in England (171 cases were presumed to have acquired mpox in the UK, 126 were acquired outside the UK and 87 are awaiting classification), 15 were in Scotland (8 were imported cases acquired outside the UK, 4 were presumed to have acquired mpox in the UK and 3 are awaiting classification), 3 were in Wales (2 were imported cases acquired outside the UK, and one was presumed to have acquired mpox in the UK), 7 were in Northern Ireland (3 were presumed to have acquired mpox in the UK, one was an imported case acquired outside the UK and 3 are awaiting classification).
Figure 1 shows the monthly number of cases in England in 2023 and 2024, where there were between one and 41 cases per month, compared to the monthly high of 1,339 cases in July 2022.
Figure 1. Number of confirmed and highly probable mpox clade IIb cases in England, by month in 2023 and 2024
Table 1. Number of confirmed and highly probable mpox clade IIb cases by UK nation of residence, 6 May 2022 to 30 November [note 1]
| UK nation | Cases reported in 2022 [note 2] | Cases presumed acquired in the UK in 2023 and 2024 | Cases presumed acquired outside the UK (imported) in 2023 and 2024 | Cases awaiting classification in 2023 and 2024 | Total (2022 to 2024) |
|---|---|---|---|---|---|
| England | 3,553 | 171 | 126 | 87 | 3,937 |
| Northern Ireland | 34 | 3 | 1 | 3 | 41 |
| Scotland | 97 | 4 | 8 | 3 | 112 |
| Wales | 48 | 1 | 2 | 0 | 51 |
| Total | 3,732 | 179 | 137 | 93 | 4,141 |
Note 1: Based on data extracted on 9 December 2024.
Note 2: Figures for 2022 start from 6 May 2022 and combine UK acquired and imported cases.
Data sources
Mpox surveillance data in England is based on mpox and orthopox virus test results from the Rare and Imported Pathogens Laboratory (RIPL), which is the UK Health Security Agency (UKHSA) mpox reference laboratory, and other UK laboratories with mpox and orthopox testing.
Counts of confirmed cases in Wales, Northern Ireland, and Scotland are submitted to UKHSA by Public Health Wales, Public Health Agency Northern Ireland, and Public Health Scotland respectively.
Information about this publication
These figures are used for official reporting of mpox confirmed case counts in the UK.
England counts may differ from those published in the Notifications of infectious diseases (NOIDs) causative agents weekly report. This is due to differences in timings of when the data is compiled, and differences in processing of duplicate data (for example, if a person has tested more than once but insufficient information is provided to identify them).
As mpox continues to be a notifiable infection, please refer to UKHSA’s NOIDs reports for weekly updates (but not cumulative totals) on laboratory-notified mpox cases in England.
While data cleaning is carried out routinely, corrections can be applied between reports, such as updates to patient information and the removal of quality assurance samples from laboratory surveillance systems.
Additional resources
Mpox outbreak: technical briefings
Mpox contact tracing guidance: classification of contacts and advice for vaccination and follow-up