Guidance

Principles for control of non-HCID mpox in the UK: 4 nations consensus statement

Updated 31 October 2024

This statement has been agreed by the UK public health agencies: UK Health Security Agency (UKHSA), Public Health Scotland, Public Health Wales and Public Health Agency Northern Ireland.

Rationale for change

Mpox is a viral zoonotic disease that is caused by the monkeypox virus (MPXV). Until May 2022, mpox was primarily identified in Central and West Africa. There are 2 historical clades of MPXV – clade I (former Central African clade) with a reported mortality of 10%, and clade II (former West African clade) with a reported mortality of 1% from epidemiological cluster and outbreak reports from Africa. Prior to 2022, it was occasionally identified in other countries related to travel from endemic areas in Central and West Africa.

Within the UK, mpox has previously been classified as a high consequence infectious disease (HCID). This is not a legal classification but agreed by the 4 nations public health agencies and the NHS to enable a consistent approach to public health and clinical management.

The rationale for classifying mpox as an HCID was that there were infrequent importations, limited information about the disease course and outcome, no confirmed availability of vaccine and unclear approaches to treatment. Therefore, it was reasonable to have a highly precautionary approach designed for complete containment around single cases in order to minimise the potential for spread.

Since 13 May 2022, cases of mpox have been reported in multiple countries that do not have endemic MPXV in animal or human populations, including countries in Europe, North America and Australasia. In the UK and other non-endemic countries, the vast majority of cases have been domestically acquired, with only a small number of imported infections. This suggests significant community transmission in multiple non-endemic countries.

Over 3,700 cases of clade II mpox have been identified in the UK since May 2022, with community transmission leading to multiple generations of spread.

The illness appears to be generally mild, though some individuals will require hospital admissions to manage secondary infections or complications from the illness. Pre- and post-exposure prophylaxis is now available.

Within clade II, The World Health Organization (WHO) has designated 2 subclades, clade IIa and clade IIb. Whole genome sequencing further divides each subclade into multiple lineages. In July 2022, the UK Advisory Committee on Dangerous Pathogens (ACDP) advised derogation of the B.1 lineage of clade IIb MPXV from HCID classification. Following consideration of additional information in January 2023, ACDP further advised that the whole of clade II MPXV should now no longer be classified as an HCID.

Importations of mpox from Central Africa, and/or mpox caused by clade I MPXV remain classified as HCIDs, as the severity of mpox caused by clade I remains unknown.

MPXV is a Hazard Group 3 organism (ACDP/HSE). Other organisms in this category include Salmonella typhi, HIV, hepatitis B and C viruses, and Mycobacterium tuberculosis. These organisms can be handled safely by most clinical microbiology laboratories with appropriate biosafety facilities. Following international agreement, from July 2022 clinical waste from mpox cases is designated as category B, and samples containing MPXV (other than viral cultures) may be carried under UN3373 via category B transport.

The following principles outlined in this document are to cover the control of non-HCID mpox within the UK. They are to help ensure a proportionate response and to deliver strategic outcomes. These principles do not replace the need for local dynamic risk assessments, which remain key.

Strategic aims

On 8 December 2022, UKHSA published the UK strategy for mpox control, 2022 to 2023. This is an overarching public health strategy for controlling mpox across the UK, agreed between the UK’s 4 public health agencies.

Audience

Professionals – to inform development of operational guidance in UKHSA, NHS and other organisations.

Assumptions about transmission and biology

These assumptions are based on the available data and expert opinion and are aligned with WHO. They will be regularly reviewed using the evidence generated in the incident response.

1. For individuals with infection who are well, ambulatory, and have either prodrome or rash, the highest risk transmission routes are direct contact, droplet or fomite. Transmission seen so far in this outbreak is consistent with very close direct contact.

2. There is some recent evidence that individuals may be infectious before the onset of symptoms. However, at the moment there is not enough evidence for pre-symptomatic transmission to justify any change in guidance. This evidence will be kept under review.

3. For individuals with infection who have evidence of lower respiratory tract involvement or severe systemic illness requiring hospitalisation, the possibility of airborne transmission has not been excluded.

4. Waste management and decontamination practice should follow best practice and be based on all the available evidence on safe handling of all waste in accordance with country specific legislation and regulations (clinical waste is now managed as Category B).

5. The highest risk period for onwards infection is from the onset of the prodrome until the lesions have scabbed over and the scabs have fallen off.

6. Deroofing procedures and throat swabs are not considered to be aerosol generating procedures (AGPs) but may cause droplets. The list of AGPs is available in the local country-specific national infection prevention and control manual.

7. There is little evidence available on the dynamics of MPXV in genital excretions, and the role this plays in transmission, so a precautionary approach is recommended: in addition to abstaining from sex while symptomatic (including during the prodromal phase and while lesions are present), condom use is recommended for 12 weeks after infection. This will be updated as evidence emerges.

8. In healthy adults, mpox is primarily self-limiting and has a relatively low mortality. There is uncertainty over potentially increased severity in children and in individuals who are immunocompromised or pregnant.

Implications

Risk assessment and consideration of the hierarchy of controls will help determine the level of personal protective equipment (PPE) to use.

Personal protective equipment (PPE)

For suspected cases, the minimum PPE is:

• gloves
• fluid repellent surgical facemask (FRSM) (an FRSM should be replaced with an FFP3 respirator and eye protection if the case presents with a lower respiratory tract infection with a cough and/or changes on their chest x-ray indicating lower respiratory tract infection)
• apron (the use of long-sleeved single-use disposable gowns should be considered where extensive manual handling or unavoidable skin-to-skin contact is anticipated)
• eye protection is required if there is a risk of splash or droplet exposure of the face and eyes (for example when taking diagnostic samples such as throat swabs)

For confirmed or highly probable cases requiring ongoing clinical management (for example inpatient care or repeated assessment of an individual who is clinically unwell or deteriorating), the minimum recommended PPE for healthcare workers is:

• fit-tested FFP3 respirator
• eye protection
• long-sleeved, fluid-repellent, disposable gown
• gloves

When classifying contacts the use of the above PPE will be considered.

Cleaning and decontamination

1. It is important to reduce the risk of fomite transmission. The risk can be substantially reduced by following existing cleaning methods based on standard cleaning and disinfection, and by washing clothes or domestic equipment with standard detergents and cleaning products.
2. Cleaning to reduce risk from the environment in community settings can be effectively achieved without using specialist services or equipment.
3. The risk of transmission in the home environment can be reduced by the case performing regular domestic cleans and washing their own clothing and bed linen in a domestic washing machine.
4. Clinical rooms should be cleaned as per standard cleaning and decontamination guidance after each patient with suspected mpox.
5. For cleaning and decontamination of the room within inpatient settings, refer to the relevant country national infection prevention and control manual and follow standard cleaning, decontamination, laundry and waste guidance.

Community and domestic

1. Home isolation may be used for clinically well, ambulatory cases (whether suspected, highly probable or confirmed) for whom it is judged by the primary clinician as safe and clinically appropriate, with ongoing clinical and public health support for clinical management and isolation.
2. For ambulatory well cases (suspected, highly probable or confirmed) with limited lesions, covering lesions and wearing a face covering or mask reduces the risk of onwards transmission.
3. Individuals with highly probable or confirmed mpox should avoid close contact with others until all lesions have healed, and scabs dried off. This should include staying at home unless requiring medical assessment or care, or other urgent health and wellbeing issues. Individuals with suspected mpox should also follow this guidance unless or until a negative MPXV test result has been received or an alternative diagnosis has been made.
4. Close household and non-household contacts of confirmed or highly probable cases should be risk assessed. Medium risk (category 2) and high risk (category 3) contacts do not need to isolate, but should avoid sexual or intimate contact with others for 21 days. High risk (category 3) contacts should also, where possible, avoid contact with children aged under 5 years and individuals who are pregnant or immunocompromised.
5. Transport from the community to healthcare facilities for well cases or individuals being assessed for mpox should be via private transport where possible. Where private transport is not available, public transport can be used but busy periods should be avoided. Any lesions should be covered by cloth (for example scarves or bandages) and a face covering must be worn.

Ambulatory care

1. For suspected, highly probable or confirmed cases, attending ambulatory healthcare (for example outpatients, emergency departments (EDs), urgent care centres, general practice, sexual health clinics), patients should be placed in a single room for assessment. The case should be provided with an FRSM to wear as appropriate.

2. Where possible, pregnant women and immunocompromised individuals (as outlined in the Green Book) should not assess or clinically care for individuals with suspected or confirmed mpox. This will be reassessed as evidence emerges.

3. Close household and non-household contacts of confirmed or highly probable cases should be risk assessed. Medium risk (category 2) and high risk (category 3) contacts do not need to isolate, but high risk (category 3) contacts should, where possible, avoid contact with children aged under 5 years and individuals who are pregnant or immunocompromised.

Inpatient healthcare

1. Where possible, pregnant women and immunocompromised individuals (as outlined in the Green Book) should not assess or provide clinical or nursing care for individuals with suspected or confirmed mpox. This will be reassessed as evidence emerges.

2. Close household and non-household contacts of confirmed or highly probable cases should be risk assessed. Medium risk (category 2) and high risk (category 3) contacts do not need to isolate, but high risk (category 3) contacts should, where possible, avoid contact with children aged under 5 years and individuals who are pregnant or immunocompromised.

Other residential settings

1. Within non-domestic residential settings (for example adult social care, prisons, homeless shelters, refuges), individuals who are clinically well should be managed in a single room with separate toilet facilities where possible.

2. In domestic and non-domestic settings where healthcare is being provided, waste generated is classified as healthcare waste and should be managed in accordance with local waste management policies.

3. Where possible, pregnant women and immunocompromised individuals (as outlined in the Green Book) should not assess or provide clinical or nursing care for individuals with suspected or confirmed mpox. This will be reassessed as evidence emerges.

4. Close household and non-household contacts of confirmed or highly probable cases should be risk assessed. Medium risk (category 2) and high risk (category 3) contacts do not need to isolate, but high risk (category 3) contacts should, where possible, avoid contact with children aged under 5 years and individuals who are pregnant or immunocompromised.