Biological principles for control of mpox in the UK: 4 nations consensus statement
Source: gov.uk (2025-03-24)

A statement on the how UK public health agencies will handle future mpox outbreaks.

This statement has been agreed by the UK public health agencies:
- UK Health Security Agency (https://www.gov.uk/government/organisations/uk-health-security-agency) (UKHSA)
- Public Health Scotland (https://publichealthscotland.scot/) (PHS)
- Public Health Wales (https://phw.nhs.wales/) (PHW)
- Public Health Agency Northern Ireland (https://www.publichealth.hscni.net/) (PHA)
This statement replaces the Principles for control of non-HCID mpox in the UK: 4 nations consensus statement, which was last updated in October 2024.

Why this is changing

Mpox is a viral zoonotic illness caused by MPXV. There are 2 distinct clades of MPXV, clade I and clade II, with 2 subclades of each (clade Ia, clade Ib, clade IIa and clade IIb).

Until May 2022, mpox was primarily reported in Central and West Africa. Since then, mpox has spread globally, with cases identified in multiple countries where mpox had not previously been reported, including the UK.

There have been at least 3 emergences from animal reservoirs leading to sustained human-to-human transmission:
- global outbreak of clade IIb MPXV in gay, bisexual or other men who have sex with men (GBMSM) in 2022 to 2023
- regional outbreak of clade Ib MPXV in affected African countries, with some exported cases from 2024
- outbreak of clade Ia MPXV in the Democratic Republic of Congo (DRC) in 2024
Mpox was classified as a high consequence infectious disease (HCID) in 2018, meaning that all cases were managed via HCID pathways in healthcare settings. In January 2023, the Advisory Committee on Dangerous Pathogens (ACDP) advised that clade II mpox no longer met the criteria for an HCID, based on evidence supporting a low case fatality rate, and mild to moderate severity illness.

During 2024, an outbreak of clade Ib mpox was reported, initially in the DRC and subsequently in neighbouring African countries. Cases had a low case fatality rate and mild to moderate illness in most cases, similar to clade II mpox. No community transmission (beyond close household contacts) has been reported for any cases of clade I mpox outside the African region. In February 2025 ACDP recommended that clade I mpox should no longer be classified as a HCID.

This means that mpox (clade I and clade II) is no longer classified as an HCID.

Assumptions about transmission and biology

The following assumptions are based on the available data and expert opinion and are aligned with the World Health Organization (WHO). They will be reviewed as new evidence becomes available.

The assumptions are:
- for individuals with infection who are well, ambulatory, and have either prodrome or rash, the highest risk transmission routes are very close direct contact, droplet or fomite
- there is some recent evidence that individuals may be infectious before the onset of symptoms. However, at present there is not enough evidence of pre-symptomatic transmission to justify any change in guidance. This evidence will be kept under review
- for individuals with an infection who have evidence of lower respiratory tract involvement or severe systemic illness requiring hospitalisation, the possibility of airborne transmission has not been excluded
- the highest risk period for onwards infection is from the onset of the prodrome until the lesions have scabbed over, the scabs have fallen off and a new layer of skin has formed underneath
- 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
- 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 (https://www.gov.uk/guidance/monkeypox-diagnostic-testing#semen-testing-for-viral-dna) – this will be updated as evidence emerges
- 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
- an effective vaccine is available for pre-exposure prophylaxis; it is also available as post-exposure prophylaxis for higher risk contacts, but efficacy is much lower compared to pre-exposure vaccination – see the Green Book chapter 29
- pox viruses can survive in the environment for up to 56 days – the risk of fomite transmission 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
Implications

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

MPXV of any clade will no longer require management through HCID pathways within healthcare settings.

Mpox remains a serious infection for some individuals, and remains a WHO public health emergency of international concern (PHEIC). The UK’s strategic aims are to reduce the impact of the introduction of clade I mpox by preventing sustained transmission, particularly within sexual networks, in the UK; and to achieve and maintain elimination of sustained transmission of clade II mpox in the UK. There will therefore be ongoing public health management of cases and contacts, including vaccination where appropriate.

MPXV remains a notifiable disease. Contact tracing and offer of post-exposure vaccination for those at highest risk and most likely to benefit are required.

MPXV remains a Hazard Group 3 organism (https://www.hse.gov.uk/pubns/misc208.pdf) (ACDP/HSE). These organisms can be handled safely by most clinical microbiology laboratories with appropriate biosafety facilities. Samples containing MPXV (other than viral cultures) may be carried under UN3373 via category B transport. See further information in Mpox: diagnostic testing (https://www.gov.uk/guidance/monkeypox-diagnostic-testing).

Clinical waste from mpox cases is designated as category B clinical waste (UN 3291).

Close contacts

Close contacts of confirmed cases should be risk assessed and managed in line with published guidance (https://www.gov.uk/government/publications/contact-tracing-guidance-for-mpox).

Personal protective equipment (PPE)

See relevant national infection prevention and control manuals or local guidance:
- England (https://www.england.nhs.uk/national-infection-prevention-and-control-manual-nipcm-for-england/)
- Scotland (https://www.nipcm.hps.scot.nhs.uk/)
- Wales (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fphw.nhs.wales%2Fservices-and-teams%2Fantibiotics-and-infections%2Fnipcm%2F&data=05%7C02%7CGillian.Armstrong2%40ukhsa.gov.uk%7C4c159482262b4fc6134308dd61648098%7Cee4e14994a354b2ead475f3cf9de8666%7C0%7C0%7C638773806482193710%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=XtRyiOVBMOBfYEdRNTmAFdWMbocbvGYKn5vr%2Fq%2Fikn8%3D&reserved=0)
- Northern Ireland (https://www.england.nhs.uk/national-infection-prevention-and-control-manual-nipcm-for-england/)
For non-healthcare settings the principles contained within the national IPC manuals should be used by organisations and employers to support local implementation and risk assessment. This should not over-ride an employer’s responsibilities under the Health and Safety at Work etc Act 1974 or any other legislation.

Cleaning and decontamination

It is important to reduce the risk of fomite transmission as pox viruses can survive in the environment and on different types of surfaces for up to 56 days depending on the environmental conditions. 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.

Cleaning to reduce risk from the environment in community settings can be effectively achieved without using specialist services or equipment.

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.

Clinical rooms should be cleaned per standard cleaning and decontamination guidance after each patient with suspected mpox.

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.

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.

Community and domestic

Home isolation may be used for clinically well, ambulatory cases (whether suspected 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.

For ambulatory well cases (suspected or confirmed) with limited lesions, covering lesions for example with clothing or a dressing reduces the risk of onwards transmission.

Ambulatory well cases (suspected or confirmed) with respiratory symptoms or oropharyngeal lesions should wear a face mask if possible, to reduce the risk of onwards transmission.

Individuals with confirmed mpox should avoid close contact with others until lesions have scabbed over, the scabs have fallen off, and a new layer of skin has grown underneath. This includes 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.

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 mask should be worn.

Waste generated by someone with mpox who is self-isolating at home can be placed in the usual domestic waste stream.

Ambulatory care

For suspected 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 a fluid-resistant surgical mask (FRSM) to wear if possible for example if no respiratory compromise and able to tolerate the mask.

Other residential settings

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.

Pregnant women and immunocompromised individuals

Where possible, pregnant women and immunocompromised individuals (as outlined in the Green Book (https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6)) should not assess or provide clinical, nursing or personal care for individuals with suspected or confirmed mpox. This will be reassessed as evidence emerges.