High consequence infectious diseases (HCID)
Source: gov.uk (2025-09-08)

Guidance and information about high consequence infectious diseases and their management in England.

Definition of HCID

In the UK, a high consequence infectious disease (HCID) is defined according to the following criteria:
- acute infectious disease
- typically has a high case-fatality rate
- may not have effective prophylaxis or treatment
- often difficult to recognise and detect rapidly
- ability to spread in the community and within healthcare settings
- requires an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely
Classification of HCIDs

HCIDs are further divided into contact and airborne groups:

contact HCIDs are usually spread by direct contact with an infected patient or infected fluids, tissues and other materials, or by indirect contact with contaminated materials and fomites

airborne HCIDs are spread by respiratory droplets or aerosol transmission, in addition to contact routes of transmission

List of high consequence infectious diseases

A list of HCIDs has been agreed by the UK 4 nations public health agencies, with advisory committee input as required.

Contact HCIDs
- Argentine haemorrhagic fever (Junin virus)
- Bolivian haemorrhagic fever (Machupo virus)
- Crimean Congo haemorrhagic fever (CCHF)
- Ebola virus disease (EVD)
- Lassa fever
- Lujo virus disease
- Marburg virus disease (MARD)
- severe fever with thrombocytopaenia syndrome (SFTS)
Airborne HCIDs
- Andes virus infection (hantavirus)
- avian influenza A(H7N9) and A(H5N1)
- avian influenza A(H5N6) and A(H7N7) [note 1]
- Middle East respiratory syndrome (MERS)
- Nipah virus infection
- pneumonic plague (Yersinia pestis)
- severe acute respiratory syndrome (SARS) [note 2]
Note 1: Human-to-human transmission has not been described to date for avian influenza A(H5N6). Human to human transmission has been described for avian influenza A(H5N1), although this was not apparent until more than 30 human cases had been reported. Both A(H5N6) and A(H5N1) often cause severe illness and fatalities. Therefore, A(H5N6) has been included in the airborne HCID list despite not meeting all of the HCID criteria.

Note 2: No cases reported since 2004, but SARS remains a notifiable disease under the International Health Regulations (2005), hence its inclusion here.

The list of HCIDs will be kept under review and updated by the UK 4 nations public health agencies, with advisory committee input as required, if new HCIDs emerge that are of relevance to the UK.

Status of COVID-19

As of 19 March 2020, COVID-19 is no longer considered to be an HCID in the UK. There are many diseases which can cause serious illness which are not classified as HCIDs.

The 4 nations public health HCID group made an interim recommendation in January 2020 to classify COVID-19 as an HCID. This was based on consideration of the UK HCID criteria about the virus and the disease with information available during the early stages of the outbreak. Now that more is known about COVID-19, the public health bodies in the UK have reviewed the most up to date information about COVID-19 against the UK HCID criteria. They have determined that several features have now changed; in particular, more information is available about mortality rates (low overall), and there is now greater clinical awareness and a specific and sensitive laboratory test, the availability of which continues to increase.

The Advisory Committee on Dangerous Pathogens (ACDP) is also of the opinion that COVID-19 should no longer be classified as an HCID.

The World Health Organization (WHO) continues to consider COVID-19 as a Public Health Emergency of International Concern (PHEIC), therefore the need to have a national, coordinated response remains and this is being met by the government’s COVID-19 response (https://www.gov.uk/coronavirus).

Cases of COVID-19 are no longer managed by HCID treatment centres only. Healthcare workers managing possible and confirmed cases should follow the National infection prevention and control manual for England (https://www.england.nhs.uk/publication/national-infection-prevention-and-control/) (or the equivalent devolved administration infection prevention and control manuals), which includes instructions about different personal protective equipment (PPE) ensembles that are appropriate for different clinical scenarios.

Status of mpox

The virus that causes mpox (MPXV) is currently divided into 2 main genetic groups (clades I and II), which subdivide into multiple lineages.

In June 2022, the ACDP recommended that the strain of the virus implicated in community transmission within the UK since mid-2022 (clade IIb, B.1 lineage) should no longer be classified as an HCID. In January 2023, the ACDP made an additional recommendation that all of clade II MPXV should no longer be classified as an HCID. At this time, ACDP recommended that clade I MPXV (formerly known as Central African or Congo basin clade) should remain an HCID. The 4 nations public health agencies reviewed this advice and agreed with the view of ACDP.

In February 2025, the evidence base for clade I MPXV was reviewed in the context of the HCID criteria, following sustained community transmission of the virus in several African Region countries, and travel-associated cases reported globally, including in the UK. The evidence was discussed by an External Assessment Group (comprising representatives from the 4 nations public health agencies and HCID network) and presented to the ACDP. In February 2025, the ACDP recommended derogation of all clade I MPXV, which was accepted by the 4 nations Chief Medical Officers, meaning that mpox is no longer an HCID.

HCIDs in the UK

HCIDs are rare in the UK. When cases do occur, they tend to be sporadic and are typically associated with recent travel to an area where the infection is known to be endemic or where an outbreak is occurring. None of the HCIDs listed above are endemic in the UK, and the known animal reservoirs are not found in the UK.

The UK has experience of managing confirmed cases of Lassa fever, EBOD, CCHF, MERS and avian influenza A(H5N1). The majority of these patients acquired their infections overseas, but secondary transmission of MERS has occurred in the UK.

Avian influenza A(H5N1) has caused outbreaks in wild birds and captive birds in the UK. In January 2022, the UK Health Security Agency (UKHSA) reported the first human case of avian influenza A(H5N1) (https://www.gov.uk/government/news/human-case-of-avian-flu-detected-in-uk) in the UK. Animal-to-human transmission of avian influenza is very rare and the risk to human health is kept under frequent review. The epidemiology and genomics of A(H5N1) virus and human health risk is actively monitored by UKHSA, in collaboration with international partners.

HCID risks by country

For health professionals wishing to determine the HCID risk in any particular country, an A to Z list of countries and their respective HCID risk is available.

See HCID country risks (https://www.gov.uk/guidance/high-consequence-infectious-disease-country-specific-risk).

Global HCID events under monitoring

UKHSA’s epidemic intelligence activities monitor potential emerging infectious disease threats, including global HCID events. Summaries of selected events can be seen on outbreaks under monitoring (https://www.gov.uk/government/collections/outbreaks-under-monitoring).

Infection prevention and control in healthcare settings

Specific infection prevention and control (IPC) measures are required for suspected and confirmed HCID cases, in all healthcare settings (specialist and non-specialist).

IPC guidance appropriate for suspected and confirmed cases of Lassa fever, EBOD, CCHF, MARD, Lujo virus disease, Argentinian haemorrhagic fever, Bolivian haemorrhagic fever and SFTS, is available in the ACDP guidance (https://www.gov.uk/government/publications/viral-haemorrhagic-fever-algorithm-and-guidance-on-management-of-patients).

IPC guidance for MERS, avian influenza, Nipah virus infection and pneumonic plague, can be found in the relevant UKHSA guidance listed below.

Links to relevant UKHSA guidance for healthcare professionals

Avian influenza (https://www.gov.uk/government/collections/avian-influenza-guidance-data-and-analysis)

Andes hantavirus (https://www.gov.uk/guidance/andes-hantavirus-epidemiology-outbreaks-and-guidance)

Argentine haemorrhagic fever (https://www.gov.uk/guidance/argentine-haemorrhagic-fever-origins-reservoirs-transmission-and-guidelines)

Lujo virus (https://www.gov.uk/guidance/lujo-virus-origins-reservoirs-transmission-and-guidelines)

MERS (https://www.gov.uk/government/collections/middle-east-respiratory-syndrome-coronavirus-mers-cov-clinical-management-and-guidance)

Nipah virus infection (https://www.gov.uk/guidance/nipah-virus-epidemiology-outbreaks-and-guidance)

Plague (https://www.gov.uk/guidance/plague-epidemiology-outbreaks-and-guidance)

VHFs, including Ebola, Marbug and CCHF (https://www.gov.uk/government/collections/viral-haemorrhagic-fevers-epidemiology-characteristics-diagnosis-and-management)

SFTS (https://www.gov.uk/guidance/severe-fever-with-thrombocytopaenia-syndrome-sfts-epidemiology-outbreaks-and-guidance)

Specialist advice for healthcare professionals

The Imported Fever Service (IFS) (https://www.gov.uk/guidance/imported-fever-service-ifs) provides 24-hour, 7-days a week telephone access to expert clinical and microbiological advice. Hospital doctors across the UK can contact the IFS after discussion with the local microbiology, virology or infectious disease consultant.

Hospital management of confirmed HCID cases

Once an HCID has been confirmed by appropriate laboratory testing, cases in England should be transferred rapidly to a designated HCID Treatment Centre. Occasionally, highly probable cases may be moved to an HCID Treatment Centre before laboratory results are available.

Contact HCIDs

There are 2 principal Contact HCID Treatment Centres for adults in England, serving the whole of the UK:
- the Royal Free London High Level Isolation Unit (HLIU)
- the Royal Victoria Infirmary HLIU in Newcastle-upon-Tyne
Further support for managing additional confirmed adult contact HCID cases can be provided by the University Hospitals of Liverpool Group (Royal Site) Royal Liverpool Hospital and the Royal Hallamshire Hospital, Sheffield, if necessary.

There are 2 Contact HCID Treatment Centres for children in England:
- the Royal Victoria Infirmary HLIU in Newcastle-upon-Tyne
- the Paediatric HCID Treatment Centre at St Mary’s Hospital in London
Airborne HCIDs

There are 7 adult and 5 paediatric Airborne HCID Treatment Centres in England:
- Guy’s and St Thomas’ NHS Foundation Trust (St Thomas’ Hospital and Evelina London Children’s Hospital; adult and paediatric services)
- Royal Free London NHS Foundation Trust (adult service only)
- Imperial College Healthcare NHS Trust (St Mary’s Hospital; paediatric service only)
- NHS University Hospitals of Liverpool Group (Royal Liverpool Hospital; adult service only)
- Alder Hey Children’s Hospital Trust (paediatric service only)
- Newcastle Hospitals NHS Foundation Trust (Royal Victoria Infirmary and Great North Children’s Hospital; adult and paediatric services)
- Sheffield Teaching Hospitals NHS Foundation Trust (Royal Hallamshire Hospital; adult service only)
- Oxford University Hospitals NHS Foundation Trust (John Radcliffe Hospital; adult and paediatric services)
- North Bristol NHS Trust (Southmead Hospital; adult service only)
During larger airborne HCID outbreaks, confirmed adult cases may also receive care in specialist regional infectious disease centres, if this has been agreed at a national level.

Travel health advice for HCIDs

The National Travel Health Network and Centre (NaTHNaC) provides travel health information about a number of HCIDs, for healthcare professionals and travellers. Advice can be accessed via the Travel Health Pro website (https://travelhealthpro.org.uk/)