Purpose
Introduction
Mass gatherings are typically defined as large numbers of people at a specific location for a specific purpose, with the gathering being large enough to strain local resources. Travelers to mass gatherings face unique risks because these events are associated with both communicable diseases (from crowding, poor hygiene practices, sanitation issues, and population dynamics [i.e., specific events attract at-risk groups]) and non-communicable conditions (e.g., temperature extremes, stampedes, environmental hazards, and challenging security situations).
Mass gathering characteristics
International travelers and their medical providers should understand the characteristics of mass gatherings. Some can be spontaneous (e.g., political protests); others are planned events. Some mass gatherings occur regularly at different locations (e.g., the Olympic Games, the Fédération Internationale de Football Association [FIFA] World Cup); other gatherings recur in the same location (e.g., Hajj, the annual Islamic pilgrimage to Mecca [see Saudi Arabia: Hajj and Umrah Pilgrimages chapter]). The Kumbh Mela, a major Hindu pilgrimage and festival in India (see India chapter) held approximately every 12 years, is the world's largest gathering of humans, attracting 100–200 million participants, including up to 50 million on a single day. Table 8.6.1 provides a brief list of mass gatherings planned in 2026, including type (religious observance, sporting event, or cultural festival), location, and anticipated attendance numbers. Most mass gatherings can be described effectively in terms of their activities, capacity, duration, location, participants, purpose, size, timing, and venue (see Table 8.6.2). Understanding health outcomes previously associated with a recurring mass gathering can help countries, event organizers, and travelers prepare for future events.
Table 8.6.1: Examples of international mass gathering events, 2026
| Event Type | Event Name | Host Country | Typical Attendance |
|---|---|---|---|
| Sporting | Olympic Games, Winter | Italy | 1.5 million |
| Religious | Hajj | Saudi Arabia | 2.5 million |
| Sporting | FIFA World Cup | Canada, Mexico, and the United States | 3 million |
| Cultural (arts/music) | Carnival | Brazil (also worldwide) | 7 million |
| Religious | Arbaeen pilgrimage | Iraq | 15–25 million |
Table 8.6.2: Mass Gatherings, Characteristic Features, and Potential Risks
Feature
Potential Risk Considerations
Activities
Some activities can be risky or strenuous (e.g., walking long distances in extreme temperatures) or could involve alcohol or drug use.
Capacity
Surveillance: Host locations differ in their ability to detect, respond to, and prevent public health emergencies.
Security: Arrangements vary.
Duration
The longer an event lasts, the more likely local resources will be depleted and become strained.
Location
Environment and infrastructure affect health and safety of events; some host countries and cities have better natural or engineered resources to handle large numbers of people than others.
Participants
Attendees can represent a unique demographic (e.g., religious, political groups) or vary by sex or age (e.g., older adults attempting to complete a religious pilgrimage toward the end of their life).
Purpose
Mass gatherings can be political, religious, cultural, or sporting events. The purpose of an event can determine the activities and affect the mood of participants.
Size
The density of crowds, not just the number of attendees, contributes to health and safety risks. More densely packed crowds can facilitate disease spread, induce riots, or cause stampedes.
Timing
Mass gatherings and local capacity are affected by the timing of an event.
Season or weather can influence the number in attendance, environmental conditions, and the types of venues needed (indoor versus outdoor), which affect the host location’s ability to organize a safe mass gathering.
Last-minute events (e.g., political rallies) may not have adequate preparation and lead to poor issue mitigation.
Venue
Indoor versus outdoor events create different sets of challenges for mass gathering organizers. Food, water, housing, and sanitation can be of varying quality.
Mass gathering-associated health concerns
Attendance at a mass gathering can exacerbate a traveler's existing medical conditions. Emergency medical services often are involved in preparations for gatherings and are usually equipped to address acute medical conditions (e.g., asthma, gastrointestinal infections, heat exhaustion, injuries, myocardial infarction).
Catastrophic incidents
Catastrophic incidents are of particular concern during mass gatherings, especially with extremely dense crowds. Numerous casualties have occurred at mass gatherings due to poor crowd management, structural collapses, fires, or violence. Crush injuries and death can result from crowding and stampedes. Stampedes are usually the result of overcapacity, poor crowd control, event spaces that lack space and unobstructed exits, inadequate support or attendee destruction of structures, and fire hazards. Recent stampedes that have resulted in deaths occurred at the 2015 Hajj pilgrimage in Saudi Arabia, at the annual Lag BaOmer festival in Israel in 2021, at a soccer match in East Java, Indonesia, in 2022, and during Halloween festivities in Seoul, South Korea, in 2022.
Ensuring personal safety during mass gatherings is necessary. Travelers should remain aware of their surroundings. If their travel plans include attendance at a mass gathering, providing travelers with information on what to do in a stampede may be beneficial (Box 8.6.1). Although the risk for large-scale incidents (e.g., terror attacks) are low, they are impossible to predict or eliminate (see Safety and Security Overseas chapter).
Box 8.6.1
Infectious diseases
Mass gathering attendees are at risk for infections, including vaccine-preventable diseases (e.g., COVID-19, influenza, pneumococcal disease). Past mass gatherings have been associated with outbreaks of influenza, meningococcal disease, and norovirus illness. Mass gatherings also have implications for global health security.
Travelers who import infectious diseases to mass gathering host sites can infect both their fellow attendees and the local population. Depending on routes of transmission, incubation periods, and other disease-specific factors, concentrations of people attending mass gatherings may amplify disease transmission. Travelers can also export communicable diseases internationally from the host location to other destinations after departing from a mass gathering.
Clinician guidance
All elements of the pre-travel consultation (see The Pre-Travel Consultation chapter) should be applied to travelers attending mass gatherings. Additional considerations specific to mass gathering attendees are provided below.
Risk assessment
Activities and itineraries
Ask travelers about their activities and itineraries. Review a traveler's itinerary to identify risks at the destination, in addition to those associated with the event itself. Travelers might add side trips or extend travel beyond the mass gathering.
Patient characteristics
Consider the patient's unique characteristics. Chronic health conditions can be exacerbated while participating in a mass gathering. Counsel patients on the importance of having adequate supplies of medication for the duration of their trip and documentation for any prescriptions. For mass gatherings that require physical activity (e.g., pilgrimages, processions), ensure that the traveler is capable of participating.
Risk mitigation
Vaccines
Encourage vaccination. Ensure that travelers have all appropriate pre-travel vaccinations, including routine and required vaccines (see Vaccination and Immunoprophylaxis—General Principles chapter).
Identify requirements for mass gathering attendees beyond those required for entry to a country. For example, whereas the Kingdom of Saudi Arabia mandates that all participants in the Hajj be vaccinated against meningococcal disease, this requirement does not apply to other travelers visiting the country. Check the Kingdom of Saudi Arabia's Ministry of Health website for up-to-date information.
In addition to any host-country requirements, some destinations and venues can have recommendations for mass gathering attendees based on public health concerns (e.g., demonstrating proof of COVID-19 vaccination). Be prepared to provide documentation as requested.
Provide education and guidance to travelers
Educate travelers on preventive measures, including regular application of sunscreen (see Sun Exposure in Travelers chapter) and insect repellent (see Mosquitoes, Ticks, and Other Arthropods chapter) and advice on how to choose safe food and beverages from vendors (see Food and Water Precautions for Travelers chapter). Emphasize the importance of regular handwashing with soap and water and the use of hand sanitizer with ≥60% alcohol content when sanitation facilities are not available.
Stay current
The Centers for Disease Control and Prevention (CDC) regularly updates its Travelers' Health website with Travel Health Notices (notifications of disease outbreaks in countries around the world) and information on select mass gatherings (e.g., Hajj, the Olympic Games).
- Gautret, P., Angelo, K. M., Asgeirsson, H., Duvignaud, A., van Genderen, P. J. J., Bottieau, E., . . . GeoSentinel Network (2019). International mass gatherings and travel-associated illness: A GeoSentinel cross-sectional, observational study. Travel Medicine and Infectious Disease, 32, 1–5. https://www.doi.org/10.1016/j.tmaid.2019.101504
- Memish, Z. A., Steffen, R., White, P., Dar, O., Azhar, E. I., Sharma, A., & Zumla, A. (2019). Mass gatherings medicine: Public health issues arising from mass gathering religious and sporting events. Lancet, 393(10185), 2073–2084. https://www.doi.org/10.1016/S0140-6736(19)30501-X
- Ranse, J., Beckwith, D., Khan, A., Yezli, S., Hertelendy, A. J., Hutton, A., & Zimmerman, P. A. (2021). Novel respiratory viruses in the context of mass-gathering events: A systematic review to inform event planning from a health perspective. Prehospital and Disaster Medicine, 36(5), 599–610. https://www.doi.org/10.1017/S1049023X21000662
- Tavan, A., Tafti, A. D., Nekoie-Moghadam, M., Ehrampoush, M., Vafaei Nasab, M. R., Tavangar, H., & Fallahzadeh, H. (2019). Risks threatening the health of people participating in mass gatherings: A systematic review. Journal of Education and Health Promotion, 8, 209. https://www.doi.org/10.4103/jehp.jehp_214_19
- World Health Organization. (2015). Public health for mass gatherings: Key considerations. https://www.who.int/publications/i/item/public-health-for-mass-gatherings-key-considerations