World Health Organization · 2025 edition · 96 pages
A comprehensive toolkit for national and subnational health authorities to conduct structured rapid risk assessments of acute public health events
- Issuer
- World Health Organization
- Edition
- 2025 edition
- Audience
- National ministries of health, national public health institutes, public health intelligence teams, IHR National Focal Points, subnational health authorities, WHO country and regional offices
- Evidence
- Expert consensus methodology, co-designed with risk assessment experts from national and international organisations, field-tested by 11 Member States from all WHO regions
- Reviewed
- 17 Oct 2026 · GMJ
What this guideline says
GMJ summary
This manual guides Member States in using the MS-RRA tool, a standardised all-hazards rapid risk assessment framework for acute public health events. The tool comprises a detailed Worksheet for analysing likelihood and impact across six structured questions, and an Output sheet for communicating findings to decision-makers. It complements the Quick and Immediate Risk Assessment (QIRA) algorithm by providing in-depth assessment when events meet specific criteria indicating need for comprehensive analysis.
The MS-RRA framework assesses three likelihood questions (exposure and susceptibility; likelihood of scale increase; response capacity to limit spread) and three impact questions (negative impact on cases; population-level impact; response capacity to mitigate impact). Teams assign categorical responses (very unlikely to almost certain; minimal to severe) and derive overall likelihood and impact estimates, optionally combining these into a risk level (low to very high). A confidence level (low, moderate, high) documents uncertainty and data limitations.
The tool supports defensible decision-making during events when standard procedures are insufficient, data are incomplete, or when events affect multiple areas or vulnerable populations. It is designed for multidisciplinary teams including epidemiologists, subject matter experts, and contextual specialists, and feeds directly into risk management actions and risk communication strategies aligned with IHR (2005) requirements.
Key points
For clinicians — doses and thresholds as stated in the guideline
- Complete risk framing before assessment: define what (hazard/disease, primary concern), why (reason for assessment), where (geographical scope), who (population at risk), when (forward-looking time frame, typically days to months), and triggers for reassessment
- Answer six structured questions: three on likelihood (exposure/susceptibility; scale increase; response capacity to limit spread) and three on impact (severity on cases; population-level impact; response capacity to mitigate impact)
- Use categorical scales: very unlikely/unlikely/likely/highly likely/almost certain for likelihood; minimal/minor/moderate/major/severe for impact; very weak/weak/moderate/strong/very strong for response capacity
- Derive overall likelihood and impact through either the driving factor approach (one question dominates) or average score approach (questions weighted 1–5, average calculated)
- Optionally assign overall risk level by combining likelihood and impact in a risk matrix: very high, high, moderate, or low
- Assign confidence level (low, moderate, high) based on information gaps, expert agreement, and inherent variability; document main sources of uncertainty in What is not known fields
- Formulate specific recommendations for each domain: to reduce likelihood or impact, improve response capacity, and fill critical data gaps; structure using the five categories (collaborative surveillance, community protection, safe and scalable care, access to countermeasures, emergency coordination)
- Initiate MS-RRA when QIRA indicates moderate/high/very high risk; event meets IHR Annex 2 notification criteria; involves unknown aetiology, high-consequence pathogen, or multiple subnational areas; or affects vulnerable populations or occurs during mass gatherings
Categorical responses and scores for overall likelihood and impact estimation
Table extracted from the guideline
| Question | Score 5 | Score 4 | Score 3 | Score 2 | Score 1 |
|---|---|---|---|---|---|
| 1. Exposure & illness likelihood | Almost certain | Highly likely | Likely | Unlikely | Very unlikely |
| 2. Scale increase likelihood | Almost certain | Highly likely | Likely | Unlikely | Very unlikely |
| 3. Response capacity (limit spread) | Very weak | Weak | Moderate | Strong | Very strong |
| 4. Negative impact on cases | Severe | Major | Moderate | Minor | Minimal |
| 5. Negative impact on population | Severe | Major | Moderate | Minor | Minimal |
| 6. Response capacity (mitigate impact) | Very weak | Weak | Moderate | Strong | Very strong |
Source: World Health Organization, User manual for the Member State Rapid Risk Assessment (MS-RRA) tool. Reproduced in summary form.
From the guideline
Verbatim
“Risk assessment is a continuous process from the detection of the signal to the response to the event.”
Editor’s perspective
Why this matters for Georgia and the region
Prof. Giorgi Pkhakadze, MD, MPH, PhD
Editor-in-Chief, Georgian Medical Journal · Chair, Public Health Institute of Georgia · WHO consultant, health and migration
As Editor-in-Chief of the Georgian Medical Journal and Chair of the Public Health Institute, I see the MS-RRA tool as directly relevant to strengthening Georgia's emergency preparedness under IHR (2005), particularly given our experience with cross-border outbreaks of measles, multidrug-resistant tuberculosis, and arboviral diseases in the South Caucasus. The tool's structured approach to documenting likelihood, impact, and confidence addresses a critical gap: our regional surveillance systems often detect events promptly through the Lugar Center and National Reference Laboratory, but defensible risk characterisation to guide targeted interventions—especially allocation of limited countermeasures or multisectoral coordination for zoonoses—has relied on ad hoc processes. I would stress to Georgian colleagues the importance of pre-establishing multidisciplinary teams (epidemiology, laboratory, clinical, regional contextual experts, and for zoonoses the National Food Agency) and conducting simulation exercises using the Worksheet before real events. One realistic implementation challenge is ensuring timely, complete surveillance data from all regions; the tool's explicit 'What is not known' fields and confidence assignment provide a transparent way to document these limitations and justify early reassessment when data improve, rather than delaying action until information is perfect.
ORCID 0000-0001-7609-4515 · Perspective written for the GMJ Guidelines Library, 17 Oct 2026
Applicability
Georgia and the South Caucasus
For Georgia and the South Caucasus, the MS-RRA tool addresses critical gaps in standardised risk assessment capacity for events ranging from communicable disease outbreaks to chemical and radiological hazards. Countries in the region with variable surveillance infrastructure and cross-border health threats (e.g., antimicrobial-resistant TB, arboviral diseases, vaccine-preventable disease outbreaks in migrant and displaced populations) would benefit from the structured, all-hazards approach. National public health institutes and subnational authorities (e.g., regional disease surveillance centres) should establish multidisciplinary teams in advance of events, including representation from the National Reference Laboratory, Lugar Center, regional health authorities, and where relevant the Ministry of Agriculture (for zoonoses) and National Environmental Agency (for environmental hazards). The tool’s explicit documentation of confidence and data gaps is particularly relevant in settings where community-based surveillance is limited and facility-based reporting may be delayed or incomplete. Integration with existing IHR (2005) focal point workflows and alignment with public health and social measures (PHSM) taxonomies would support regional harmonisation and cross-border collaboration for shared threats.
Questions this guideline answers
Quick answers
When should we use the MS-RRA tool instead of the QIRA algorithm?
Use MS-RRA when an event requires in-depth analysis beyond QIRA's immediate assessment: when QIRA indicates moderate/high/very high risk; when the event meets IHR Annex 2 notification criteria; for unknown aetiology or high-consequence pathogens; when multiple subnational areas are affected; when the event is not unfolding as expected; or when high public or political concern necessitates detailed, defensible recommendations. QIRA takes <1 hour and provides generic prespecified actions; MS-RRA takes several days, involves a multidisciplinary team, and generates event-specific recommendations and detailed rationale.
How do we choose the time frame (forward-looking window) for the assessment?
The time frame should match how rapidly the event is evolving and the scale needed to inform action. For fast-moving events (e.g., explosive outbreak, novel pathogen), use 3 days to 2 weeks. For slower events (e.g., endemic disease with gradual increase), use 1–3 months. The time frame is not the deadline to complete the assessment but the future period the assessment covers when estimating likelihood of worsening and potential impact. It may also link to when reassessment is triggered (e.g., reassess after the time frame expires or if new information emerges that changes risk).
How should we handle situations where the risk differs across populations or geographical areas?
You have three options: (1) complete the Worksheet for the main population/area and highlight other higher-risk strata descriptively in the Output sheet; (2) complete separate Worksheets and Output sheets for each stratum; or (3) assess multiple strata within one Worksheet by providing stratum-specific information where differences occur (not every cell needs stratification), duplicating the overall likelihood/impact estimation tables for each stratum, and using the alternative Output table format to report stratum-specific estimates, risk statements, and recommendations.
What confidence level should we assign if data are limited but the potential impact is severe?
Assign a low confidence level if critical information gaps exist, there is low expert agreement on key aspects, or inherent variability is high/uncharacterised. Document the main data limitations in the 'What is not known' fields and the Output sheet. Even with low confidence, you should still estimate likelihood and impact using best available evidence and expert judgement. If current data indicate potential for significant public health effects, consider rating response capacity as weak or very weak until new data arrive, and highlight the need to fill critical data gaps as a key recommendation. Low confidence signals that the assessment may change substantially when more information becomes available, providing a clear rationale for early reassessment.
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- Issuer
- World Health Organization
- Type
- Manual
- Edition
- 2025 edition
- Status
- Current
- Published
- 2026-09-09
- Languages
- English
- Scope
- All-hazards rapid risk assessment for acute public health events at national and subnational levels
- Audience
- National ministries of health, national public health institutes, public health intelligence teams, IHR National Focal Points, subnational health authorities, WHO country and regional offices
- Pages
- 96
- Licence
- CC BY-NC-SA 3.0 IGO
- ISBN
- 978-92-4011938-3
- Evidence
- Expert consensus methodology, co-designed with risk assessment experts from national and international organisations, field-tested by 11 Member States from all WHO regions
- Record history
- Created 17 Oct 2026 · updated 17 Oct 2026 · next check Apr 2027
User Assessment (MS-RRA) tool. Geneva: World Health Organization; 2025. Licence: CC BY-NC-SA 3.0 IGO.GMJ Guidelines Library records are original summaries written by the GMJ editorial team from the issuer’s published document and reviewed by a physician. They do not replace the full guideline. The document is the copyright of its issuer and is linked, not hosted. Spotted an error or a newer edition? Tell the Guidelines Desk.
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