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Mpox clade IIb monthly cases

Last updated on Thursday, 16 October 2025 at 09:15am

Summary

Topic
mpox-clade-2b
Category
cases
API name
mpox-clade-2b_cases_countByMonth

Rationale

The timely identification of cases is important to controlling the spread of mpox and reducing the burden on healthcare systems.

Definition

This metric shows the total count of mpox clade Ib cases for England by month of specimen date.

Methodology

Mpox surveillance data for England is based on test results from the Rare and Imported Pathogens Laboratory (RIPL). RIPL is the UKHSA mpox reference laboratory and includes tests for mpox and orthopox. Other laboratories testing for mpox and orthopox in the UK also contribute to mpox surveillance data.

We use a positive mpox polymerase chain reaction (PCR) test to classify a suspected sample of mpox as a confirmed case. RIPL also conducts genetic analysis, known as clade typing, to further categorise the case into clades. An individual with a positive mpox PCR test result and clade typing result of clade IIb is defined as a case of mpox clade IIb.

Local and regional laboratories report all positive mpox PCR tests to UKHSA via the Second Generation Surveillance System (SGSS). SGSS is an application that stores and manages data on laboratory isolates and notifications. It is the preferred method for capturing routine laboratory surveillance data on infectious diseases and antimicrobial resistance from diagnostic laboratories across England.

Laboratory data for mpox is extracted from SGSS, cleaned, deduplicated and then enhanced with data from UKHSA’s Case and Incident Management System (CIMS). CIMS is used to record and control activity and decisions taken in managing cases, incidents, situations, outbreaks and enquiries. This information is used to generate a dataset listing mpox clade IIb cases in England. This is known as the national line list. The line list used for reporting weekly numbers is generated on Mondays.

Caveats

The SGSS is a live system and is therefore provisional and subject to change. Additionally, there is an estimated delay of up to five days between a sample being confirmed as mpox clade IIb and the report appearing in the SGSS and the national line list. Cases confirmed after the weekly line list is generated on a Monday will not appear in the total count of cases until the following week’s update.

Corrections can be applied between updates, such as enhancements to patient information and the removal of quality assurance samples from laboratory surveillance systems.

As mpox continues to be a notifiable infection, weekly case counts are separately published in the UKHSA’s weekly notifications of infectious diseases (NOIDs) in England report.

Routine monthly updates on both clade Ib and clade IIb mpox cases in the UK are also separately published.

Case counts presented within the UKHSA data dashboard may not align with those published in these related statistical outputs, due to differences in timings of when initial provisional data, and any later revisions, are compiled and published.

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