World Health Organization · 1st edition, 2025 · 48 pages
Operational guidance for conducting simulation exercises and after action reviews to enhance mass gathering health preparedness and response
- Issuer
- World Health Organization
- Edition
- 1st edition, 2025
- Audience
- Host countries, event organizers, health authorities, government officials, emergency services, multisectoral stakeholders involved in mass gathering planning and delivery
- Evidence
- Expert consensus, consultations with WHO Regional MG Focal Points, WHO Mass Gathering Collaborating Centres, event organizers, and literature review
- Reviewed
- 14 Oct 2026 · GMJ
What this guideline says
GMJ summary
This practical guide provides host countries, event organizers, health authorities, and stakeholders with operational tools to test preparedness for managing mass gathering (MG) events through simulation exercises (SimEx) and evaluate performance through after action reviews (AAR). Mass gatherings – sporting events, religious pilgrimages, concerts, festivals – strain health resources and pose public health risks including infectious disease outbreaks, crowd surges, environmental threats, and mass casualties.
The guide embeds SimEx and AAR within an eight-step preparedness cycle: stakeholder engagement, risk assessment, emergency preparedness and response plan (EPRP) development, simulation exercises, EPRP revision, event delivery, after action review, and event legacy documentation. It provides four adaptable hazard-specific scenarios (foodborne outbreak, crowd surge, chemical spill, heatwave) for discussion-based exercises, along with facilitator guides, concept note templates, participant guides, and feedback forms.
The AAR component includes a comprehensive trigger question database organized by technical pillars to facilitate structured post-event learning. Both SimEx and AAR should be directly linked to findings from all-hazards risk assessments and contribute to strengthening health systems, workforce capacity, public health infrastructure, and International Health Regulations (IHR) core capacities beyond individual events.
Key points
For clinicians — doses and thresholds as stated in the guideline
- Conduct simulation exercises after risk assessment is completed but with sufficient time before the event to implement findings and address identified gaps
- Plan AAR activities during event preparedness phase; conduct initial debrief immediately after event closure, followed by comprehensive AAR within three months
- Involve multisectoral stakeholders including event organizers, Ministry of Health, regional/local health authorities, ambulance services, hospitals, laboratories, NGOs, security forces, media, religious organizations, and tourism agencies
- Discussion-based exercises (tabletop) should test four core areas: roles and responsibilities, coordination mechanisms, communication channels, and risk communication and community engagement (RCCE) procedures
- SimEx should be 4–5 hours duration including sessions, recaps, and debrief; allocate sufficient time for post-exercise debrief to identify strengths, gaps, and recommendations
- Draft SimEx report within one month of exercise; assign specific actions to individuals with clear deadlines for implementation before the event
- AAR methods include small group debriefs, working group meetings, key informant interviews, questionnaires, surveys, and case studies; engage participants who leave immediately after events
- Link AAR to event legacy evaluation: infrastructural improvements, health-care surge capacity, hygiene promotion, and cross-sector communication channels that persist after events end
Exercise Management Team Roles and Responsibilities
Table extracted from the guideline
| Role | Key Responsibilities |
|---|---|
| Exercise Manager | Single person supervising overall conduct; ensures exercise proceeds as planned and objectives are reached; provides welcome, briefing, starts exercise, ensures timekeeping, conducts debrief; drafts exercise report with recommendations and timeline |
| Facilitator(s) | Delivers injects and monitors progress; first point of contact for questions; supports exercise manager; remains neutral without providing direct answers; encourages discussion while maintaining flow |
| Evaluator(s) | Gathers data and analyses whether objectives/targets were met; evaluates overall performance, operational effectiveness, quality control, capabilities, strengths/weaknesses, areas for improvement |
| Participants | Persons performing their function and tasks as during real emergency response; act in real-life roles; work as team; focus on solutions; record discussions; provide feedback to wider group |
Source: World Health Organization, Mass gathering practical guide for simulation exercises and after action reviews. Reproduced in summary form.
From the guideline
Verbatim
“Simulation exercises are critical activities for assessing existing systems, plans and protocols, identifying potential gaps, and addressing the gaps between the existing healthcare system and the specialized medical services established specifically in advance of the MG 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 Georgia increasingly hosts international sporting events, religious pilgrimages attracting regional visitors, and cultural festivals, this WHO practical guide addresses a genuine preparedness gap in our national emergency response framework. The simulation exercise scenarios – particularly crowd surge and foodborne outbreak – are directly applicable to events like Tbilisoba or matches at Dinamo Arena where we have seen resource strain. I would emphasize to Georgian colleagues the recommendation to conduct SimEx after completing the all-hazards risk assessment but with sufficient lead time to implement findings before the event; too often we have seen preparedness activities compressed into the final weeks. The realistic implementation challenge for Georgia will be securing dedicated budget allocation for SimEx and AAR within municipal and national event planning processes, as these are often viewed as optional rather than integral to public health protection, and ensuring continuity when staff from the National Center for Disease Control, Ministry of Internal Affairs, and local municipalities who participated in planning move to other positions before knowledge transfer occurs.
ORCID 0000-0001-7609-4515 · Perspective written for the GMJ Guidelines Library, 14 Oct 2026
Applicability
Georgia and the South Caucasus
Georgia hosts diverse mass gatherings including religious pilgrimages (Orthodox Christian festivals), sporting events, cultural festivals, and increasingly international conferences. This guide is directly applicable to national and municipal authorities preparing for events such as Tbilisoba Festival, international football matches, and religious observances at major monasteries. Georgian public health authorities should integrate MG preparedness into the national IHR core capacity strengthening programme and Emergency Operations Centre functions. Given Georgia’s experience managing COVID-19 during public gatherings and ongoing strengthening of emergency medical services, the simulation exercise scenarios can be adapted to test coordination between the National Center for Disease Control and Public Health, Ministry of Internal Affairs, local municipalities, and event organizers. The AAR methodology is particularly relevant for documenting lessons from recurring events and building institutional memory as staff turnover occurs in Georgian health institutions.
Questions this guideline answers
Quick answers
When should simulation exercises be conducted in relation to a mass gathering event?
SimEx should be planned after the risk assessment is completed, since findings inform the exercise purpose, objectives, and scenario. Schedule the SimEx with sufficient time remaining before the event to implement any findings and address gaps identified during the exercise. This requires early planning, ideally embedding SimEx considerations into the overall event preparedness timeline.
What types of stakeholders should participate in mass gathering SimEx and AAR?
Key stakeholders include health authorities (Ministry of Health, regional/local health departments), event organizers, government authorities (municipal, regional, national), emergency management agencies, medical service providers (onsite medical personnel, hospitals, ambulance services), law enforcement and security, communications and media entities, and community groups/NGOs. Not all need direct MG expertise but should be involved if they would respond to incidents during the event.
How soon after an event should an after action review be conducted?
AAR should be embedded in planning, with initial debrief conducted immediately after the event ends to capture urgent takeaways, as many stakeholders may leave positions or locations following the event. Follow up with more in-depth activities (surveys, interviews, meetings) days or weeks later. Complete comprehensive AAR within three months of event closure to ensure findings inform future events while memories remain fresh.
What are the main challenges in conducting SimEx and AAR for mass gatherings?
Challenges include limitations of time and resources (financial and human), lack of intersectoral coordination, insufficient understanding of SimEx/AAR value, political constraints, events not fully organized until weeks/days before start due to economic constraints, difficulty retaining key stakeholders for AAR if they leave immediately after events, and failure to plan AAR activities in advance. Awareness-raising and political will are needed to demonstrate benefits versus simply reviewing past events.
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Quality & accreditation
- ASF PHC — Standard 4 — Acute & Same-Day Care · Primary Health Clinic
- ASF PHC — Standard 7 — Governance & Staffing · Primary Health Clinic
- ASF Hospital — Standard 5 — Safety & Emergency Preparedness
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- Issuer
- World Health Organization
- Type
- Guideline
- Edition
- 1st edition, 2025
- Status
- Current
- Published
- 2025-07-21
- Languages
- English
- Scope
- Mass gathering events (sporting, cultural, religious, entertainment, business, political) at local to global scale
- Audience
- Host countries, event organizers, health authorities, government officials, emergency services, multisectoral stakeholders involved in mass gathering planning and delivery
- Pages
- 48
- Licence
- CC BY-NC-SA 3.0 IGO
- ISBN
- 978-92-4-010484-6
- Evidence
- Expert consensus, consultations with WHO Regional MG Focal Points, WHO Mass Gathering Collaborating Centres, event organizers, and literature review
- Record history
- Created 14 Oct 2026 · updated 14 Oct 2026 · next check Apr 2027
World Health Organization. Mass gathering practical guide for simulation exercises and after action reviews. 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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