HCID status of mpox (monkeypox)
Information on the status of mpox as a high consequence infectious disease (HCID).
Background
A high consequence infectious disease (HCID) is defined as:
- an acute infectious disease
- typically having a high case-fatality rate
- not always having effective prophylaxis or treatment
- often difficult to recognise and detect rapidly
- able to spread in the community and within healthcare settings
- requiring an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely
HCID status is conferred by the UK 4 nations public health agencies, with advisory committee input as required. It is used to determine the appropriate clinical and public health response pathways. It has no standing in law. It does not of itself affect the classification of the pathogen in terms of hazard group, the management of waste or transport requirement.
Reviews in relation to mpox
June 2022
The Advisory Committee on Dangerous Pathogens (ACDP) recommended that the strain of monkeypox virus (MPXV) currently in community transmission within the UK (Clade IIb, B.1 lineage) should no longer be classified as an HCID.
January 2023
The ACDP recommended that all of Clade II MPXV (formerly West African clade) should no longer be classified as an HCID.
ACDP recommended that Clade I (formerly known as Central African or Congo basin clade) should remain an HCID. The 4 nations public health agencies have reviewed this advice and agreed with the view of ACDP.
Different types of MPXV
MPXV is currently divided into 2 main genetic groups (Clades I and II), which subdivide into multiple lineages.
Clade I
Originally known as the ‘Central African’ or ‘Congo Basin’ clade, this is more likely to cause severe mpox disease. To date, there have been no Clade I cases in the UK, and this clade has not been implicated in the outbreak that started in mid-2022.
Clade II
This was formerly known as the ‘West African’ clade and appears to cause less severe mpox disease in humans than Clade I. Clade II has been further subdivided into Clades IIa and IIb.
Clade IIa
Isolates from this clade have previously been reported in West Africa. No cases from this clade have been seen in the 2022 outbreak.
Clade IIb
Clade IIb is the group of variants largely circulating in the global outbreak that started in mid 2022. There are several lineages of Clade IIb that are genetically distinct. The B.1 lineage is the main outbreak strain currently in circulation in the UK – all UK-acquired mpox cases genetically sequenced so far are part of this lineage.
A small number of Clade IIb, non-B.1 lineage travel-associated cases have also been identified.
Further information on the genomic epidemiology of MPXV is available.
Other implications
HCID network
Most patients with non-HCID mpox who have mild symptoms and who are able to self-isolate will be managed as outpatients with follow-up via a virtual ward or similar, by local sexual health or infection services. However, the NHS in all 4 nations will continue to draw on the expertise of HCID units in the assessment and management of cases requiring admission to hospital. This reflects the potential for severe disease due to any clade in vulnerable groups. In addition, there may be specific infection control risks in patients with extensive disease where input from the HCID network may be helpful.
Waste, transport and laboratory requirements
There is no change to waste, transport or laboratory regulatory requirements as a result of the HCID derogation. By international agreement, samples and waste from all mpox cases are classified as Category B for transport and waste management. Laboratory cultures of MPXV remain classified as Category A.
Personal protective equipment (PPE)
There is no automatic change to personal protective equipment (PPE). Recommendations are outlined in the 4 nations principles document and relevant national infection prevention and control (IPC) guidance.
There is no automatic change to the public health response. The decisions on stringency of approach remain with the incident management team (IMT) and will be decided on the basis of the public health risk assessment.
Updates to this page
Last updated 14 August 2024 + show all updates
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Removed 'Operational definitions' section. This can now be found on the Operational mpox (monkeypox) HCID case definition page.
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Updated in line with the HCID derogation of all Clade II mpox.
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Updated information about the definition of HCID.
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First published.