Guidance

HAIRS risk assessment process

Updated 26 January 2023

About the group

This information was prepared by the UK Health Security Agency (UKHSA) on behalf of the joint Human Animal Infections and Risk Surveillance (HAIRS) group. HAIRS is chaired by the Department for the Environment, Food and Rural Affairs (Defra), with secretariat functions provided by UKHSA’s Emerging Infections and Zoonoses team.

HAIRS is a multi-agency cross-government horizon scanning and risk assessment group. It aims to identify and risk assess emerging and potentially zoonotic infections which may pose a threat to UK public health.

Members of HAIRS

The group includes representatives from:

• UKHSA
• Defra
• the Department of Health and Social Care (DHSC)
• the Animal and Plant Health Agency (APHA)
• the Food Standards Agency
• Public Health Wales
• Welsh Government
• Public Health Scotland
• Scottish Government
• Public Health Agency of Northern Ireland
• the Department of Agriculture, Environment and Rural Affairs for Northern Ireland
• the Department of Agriculture, Food and the Marine
• Health and Safety Executive
• Republic of Ireland, Infrastructure, Housing and Environment
• Government of Jersey
• Isle of Man Government
• the States Veterinary Officer, Bailiwick of Guernsey

Development of risk assessment processes

Since the HAIRS group was established in early 2004, there has been a steady evolution and development of the risk assessment processes used by the group.

The initial methods and sources used for identifying, assessing and reporting potential threats were developed to fulfil the functions of the Chief Medical Officer’s National Expert Panel on New and Emerging Infections (NEPNEI). Thus, all activities were agreed and approved by the NEPNEI panel.

NEPNEI was disbanded in 2012 and HAIRS now reports to the Advisory Committee on Dangerous Pathogens (ACDP) and the UK Zoonoses, Animal Diseases and Infections group (UKZADI). HAIRS group members also report to their government ministries and agencies.

Multi-step process for risk assessments

The following is an overview of the process used by the group in the assessment of new and emerging threats of potential significance to the health of the UK public:

• hazard identification
• hazard review (information assimilation, preliminary review, determination of action)
• risk assessment (evidence gathering, assessment of the zoonotic risk or probability of infection in the UK population, assessment of the UK human health impact)
• risk management options
• risk communication

Hazard identification

Potential zoonotic agents, syndromes or emerging infections are identified by members of the HAIRS group. These can include incidents or reports derived from epidemic intelligence activities (for example, UKHSA’s global horizon scanning), acute clusters and outbreaks, or increasing trends of known infections or syndromes and reports of new infections or undiagnosed syndromes identified via scanning surveillance within the UK. Where human-to-human transmission is already occurring, the identification of a potential animal reservoir or spill-over host can be required.

HAIRS members also act as a focus through which concerns of their respective agencies or organisations can be considered by the group. Epidemic intelligence activities undertaken by individual agencies and organisations will vary depending on individual remit. However, they will incorporate monitoring of a wide range of official reports, scientific publications and unofficial sources (such as grey literature and media reports).

Depending on the perceived urgency of the situation, issues highlighted by members or significant results of epidemic intelligence activities are either disseminated within the group via email for immediate consideration, or are distributed with meeting papers and discussed as a standing agenda item at the next monthly meeting.

All potential hazards discussed by the HAIRS group are recorded by the secretariat in the issues discussed log and are reviewed at the face-to-face meetings.

Hazard review

A 3-step process is used by the group to review newly identified hazards.

Step 1: initial information gathering

A brief overview of all currently available information on the identified hazard is assembled by the secretariat with the assistance of appropriate members. This summary of assimilated information is provided to all members for consideration ahead of further discussions (see following steps). For novel or emerging agents, there is usually limited information available, and so parallels with related agents or expert opinion are often important at this early stage to ensure the most appropriate information is considered.

Step 2: preliminary review

The group reviews the summary information and discusses further actions as required. This may be done by email, ad-hoc teleconference or at a scheduled monthly meeting. If required, external subject matter experts can be consulted at this stage, and further stages (see Step 3). If the initial review suggests there may be major public health implications from the hazard, this is immediately summarised, escalated and an expert group may be convened.

Step 3: determination of actions required

Following the initial review, a consensus decision is reached by members on the most appropriate action required.

A. Only record hazard in log

If the identified hazard is not considered a substantial risk to public health, the hazard is recorded in the issues discussed log. The group may decide to take no further action and ‘sign off’ the hazard. Nevertheless, the group continues to monitor the situation and literature on the agent to ensure there are no emerging issues.

B. Risk review statement

A risk review statement may be undertaken when:

• the information available is insufficient for a formal risk assessment
• a comprehensive risk assessment was not deemed necessary at the time
• an urgent assessment of the risk is required before a formal assessment can be carried out. In this case, an interim risk review statement may be produced while the full risk assessment is completed. See Appendix A for HAIRS risk review statement template

C. Formal risk assessment

If a risk assessment is deemed necessary, it is carried out by the most appropriate HAIRS members in consultation with the wider group and, if appropriate, recognised external subject matter experts. Agreed algorithms to assist in the risk assessment have been developed to provide uniformity to the process. These are the zoonotic potential and emerging infections algorithms. The most appropriate algorithm is used for the hazard under assessment.

If neither of the above algorithms are considered appropriate for the hazard under review, a descriptive qualitative risk assessment can be undertaken.

Risk assessment

Gathering evidence

A full systematic review of the scientific literature is undertaken for each risk assessment, guided by questions within each of the respective algorithms. All sources used in estimating the risk are recorded and included in the document.

For assessments with insufficient information from traditional sources (for example, peer-reviewed literature), expert opinion is sought at an early stage. Personal experience and expert opinion may be included in the risk assessment document but the source is very clearly documented.

Case reports, non-peer reviewed studies and other grey literature may be included, but this is clearly distinguished from other evidence sources. An assessment of the quality of evidence is undertaken for all risk assessments (see Appendix B), and this allows for a degree of confidence in the estimation of risk to be clearly stated.

Risk assessment algorithms

The risk assessment algorithm used for each identified hazard is circumstance dependent. A fixed set of questions is applied to risk assess identified hazards. Using the guidance of the algorithm, the evidence to support answers to each question is recorded in information tables with full referencing. For both sets of algorithms, the probability of either zoonotic risk or infection in the UK human population, as well as the potential impact on the UK public health, are reported separately to offer greater clarity of the nature of the risk.

In the event that a pathogen of concern is already circulating widely in the human population, the assessor should consider the likelihood for reverse zoonosis. Of particular concern is where a new variant, reassortment or antimicrobial agent resistant strain could arise as a result of cycling through an animal population and cause new zoonotic infections.

Zoonotic potential and UK threat assessment algorithms

The zoonotic potential risk assessment algorithms are used for either newly identified animal pathogens, or animal syndromes for which an aetiological agent has not yet been identified.

A. Qualitative assessment of the zoonotic potential of an identified animal pathogen

This algorithm is used for assessing the risk of newly described, emerging or re-emerging animal diseases for which the aetiological agent has been identified as infectious.

B. Qualitative assessment of the zoonotic potential of a novel animal syndrome of unknown aetiology

This algorithm is used for assessing the risk of newly described, emerging or re-emerging animal syndromes for which the aetiological agent has not yet been determined. Following initial assessment, if the aetiological agent is determined as infectious in nature, the risk assessment is repeated using the algorithm estimating the zoonotic potential of an identified animal pathogen.

For both algorithms, if the agent or syndrome is regarded as potentially zoonotic (level 2 or above), a qualitative UK public health threat assessment is also completed to assist in considering further actions required.

These algorithms were implemented in October 2018 (see Appendix C for full details). Prior to this, the algorithm described in the scientific literature by Palmer and colleagues in 2005 was used (1).

Emerging infection and UK impact assessment algorithm

The emerging infections risk assessment algorithm is used for recognised emerging zoonotic or other emerging infections. The algorithm assesses the likelihood of the agent causing infection in the UK human population, as well as its potential impact on the health of the UK population.

The requirement for this risk assessment is normally triggered by a change in either the epidemiology of the disease (for example, emergence, re-emergence or increased incidence), the pathogenesis of the agent (for example, increases in associated human morbidity and/or mortality), or host specific factors (for example, newly recognised host or increasing geographical range).

The algorithm has been in use since 2005 (see Appendix D for full details) and has been described in the scientific literature by Morgan and colleagues in 2009 (2). In July 2022, the algorithm was reviewed to clarify it was still fit for purpose. Following this review, the algorithm was edited so that it could account for reverse-zoonosis events concerning a pathogen already involved in widespread human-to-human transmission, with consideration to the additional transmission risk and impact posed by, for example, an animal-derived variant, as a result of cycling through an animal population.

Conveying uncertainty

If a question in an algorithm cannot be conclusively answered by a yes or no response, then evidence for both answers should be provided in the information tables. Following precautionary principles, the algorithm should be continued until a decisive answer is attained. Uncertainty in the response is differentiated from a conclusive answer by the use of hatching in the algorithm.

Assessing the level of confidence in the assessment

Once the algorithm has been completed, the level of confidence in the assessment of risk is assessed by examining the quality of evidence in the information tables that underpin the risk assessment (see Appendix B). The level of confidence in the assessment is presented on the front cover of each risk assessment document.

Risk management options

HAIRS is a risk assessment group rather than a risk management group. In each assessment completed by the HAIRS group, recommendations for risk management options may be presented (see Appendix E).

Risk management recommendations will be communicated to the most appropriate policy makers and cross-government groups to inform risk management decisions and action. This may include alerting risk groups or developing and issuing guidance for a particular hazard.

In circumstances in which the evidence used to assess the risk is deemed unsatisfactory, the HAIRS group may continue to monitor the situation and reassess the risk at appropriate intervals.

Members of the group may act as points of contact for the agencies and departments responsible for risk management. Thus, although the HAIRS group will not act directly as a risk manager, its members may contribute advice and expertise to the risk management process.

Risk communication

Communication of risk assessments may take various forms depending on how the potential risk was raised, the estimated risk, or the context surrounding the situation or incident. Risks assessed as high are immediately escalated and communicated.

All risk assessments and risk statements are agreed and signed off by HAIRS members representing their organisations.

HAIRS members are responsible for the distribution and alerting of risk assessments and statements within their respective agencies or organisations. In certain circumstances, an abridged version of the full risk assessment may be deemed most appropriate for wider distribution.

Risk assessments with good enough evidence to support the outcome are placed in the public domain on the HAIRS group webpage on GOV.UK.

Completed risk assessments are communicated to ACDP and the UKZADI, and the UK Public Health Network for Zoonoses as appropriate. For specific situations, a narrative risk statement or summary may be appropriate.

In addition, summary versions of risk assessments are also published in the public domain in the HAIRS group annual reports.

Risk review and revision

If significant changes in the epidemiology or knowledge base affecting the risk estimation of a pathogen are reported, the risk assessment will be reviewed by HAIRS group members. If appropriate, the choice of algorithm used is reviewed.

Otherwise, to ensure the information in the risk assessments remains current, all assessments are reviewed annually and updated using any new information and evidence.

The date the risk assessment was completed (or the most recent review and update), the version, and if appropriate, the reason for the update, is clearly noted on all risk assessment documents.

References

1. Palmer S, Brown D, Morgan D. Early qualitative risk assessment of the emerging zoonotic potential of animal diseases. BMJ. 2005;331(7527):1256-60.

2. Morgan D, Kirkbride H, Hewitt K, Said B, Walsh AL. Assessing the risk from emerging infections. Epidemiol Infect. 2009;137(11):1521-30.

Appendices

Appendix A. Risk review statement template

This template is available to download as a Word document.

Appendix B. Assessing the quality of evidence and confidence in the risk

This information helps to determine the quality of evidence and confidence in the risk.

Appendix C. Zoonotic risk algorithms

These zoonotic risk algorithms are available to download in a flowchart format, along with an accessible text alternative, as a PDF.

Appendix D. Emerging infection algorithms

These emerging infection algorithms are available to download in a flowchart format, along with an accessible text alternative, as a PDF.

Appendix E. Risk management options

This information provides examples of actions for risk managers following assessments of risk.