Risk-informed decision-making for mass gatherings during COVID-19 pandemic

Objective: Provide a framework for risk-informed decision making about mass gatherings during the COVID-19 pandemic.

Audience(s): Event organizers and planners can use this document to consider risks associated with mass gatherings, the implementation of risk mitigation strategies, and in consultation with local public health authorities (PHA) regarding decisions to cancel or postpone events. PHA can use this tool to support decision-making about mass gatherings in their jurisdictions.

What are mass gatherings?

  • Mass gatherings are settings or events where large numbers of people may be in close contact.
  • Examples include spiritual and cultural events, performances, sporting events, festivals, and conferences.

What are the public health risks of mass gatherings during the COVID-19 pandemic?

  • Mass gatherings can contribute to the transmission of respiratory pathogens, such as the virus that causes COVID-19.
  • Mass gatherings that attract participants from other affected countries or regions may increase the risk of its importation to Canada, and/or promote its spread within Canada.

Should mass gathering plans be changed during the COVID-19 pandemic?

  • The Public Health Agency of Canada recommends that event organizers and planners cancel or postpone in-person gatherings in alignment with the recommendations of their local public health authorities, and where possible, offer virtual/online alternatives.
  • Mass gatherings are all different, so planning decisions must be done on a case-by-case basis.
  • The Public Health Agency of Canada (PHAC) recommends that this risk assessment framework be used to systematically consider the characteristics of the mass gathering and its participants, identify risks and their weight (importance) in decision-making, understand the public health rationale, and consider risk mitigation strategies.
  • The social and economic impacts of cancelling or postponing mass gatherings must also be considered.
  • The local PHA can be consulted for further guidance.
  • Risk-informed decisions about public health actions may range from enhancing communications to participants, to implementing risk mitigation strategies, to postponing or cancelling the event.

What is currently known about the virus that causes COVID-19?

  • This virus transmits readily by respiratory droplets and contact, suggesting that attendance at a mass gathering could result in transmission if a case is present.
  • It is possible that the virus is transmitted in the early phase of illness, when symptoms are non-specific or mild, therefore mass gathering participants may not know they are ill and contagious.
  • COVID-19 manifests as a non-severe disease in most cases (~80 %), with a smaller proportion of cases developing severe pneumonia, and some dying.
  • People at higher risk of complications and severe disease include the elderly, and people with underlying chronic or immunocompromising medical conditions.
  • The estimated incubation period (the time between catching the virus and symptom onset) is 5-6 days on average, ranging from 1 to 14 days. People who have been exposed prior to the mass gathering could become ill and contagious at the mass gathering. Also, if people are infected at the mass gathering, they may not show any sign of illness until after returning home, which could result in geographic spread of the disease.

Risk assessment framework

This risk assessment framework for mass gatherings in the Canadian context is based on advice from the World Health Organization’s mass gathering guidance Footnote1, the US Centre for Disease Control’s guidance Footnote2 and on public health assumptions that reflect the currently available scientific evidence and expert opinion. It is subject to change as new information on transmissibility and epidemiology becomes available. For information regarding COVID-19, including other community-based public health guidance, visit the Canada.ca and WHO web sites.

Event Participants / Population at Risk
Event Participants / Population at Risk
Characteristics Risk considerations Public health rationale Weight Risk mitigation strategies
Population attending the event How many people are expected to attend the event? The larger the number of participants, the greater the likelihood of a participant being a case of COVID-19. Large numbers of people may also create greater likelihood of crowding and close contact. High importance
  • Reduce the number of participants or change the venue to prevent crowding.
Are participants coming from affected areas where COVID-19 has been detected? If participants are expected from affected areas, the risk of importation is higher. These travellers may be self-monitoring for symptoms of COVID-19 or self-isolating for 14 days from their arrival in Canada, based on public health advice provided upon entry to Canada. High importance
  • Plan for information sharing, risk communication, and emergency communications;
  • Communicate personal preventive strategies: stay home if ill, practice hand hygiene and respiratory etiquette, avoid touching your eyes, nose, and mouth with unwashed hands;
  • Consider accessibility of communications (e.g. multiple languages, plain language);
  • Develop flexible refund policies for participants to promote staying home when sick;
  • Consider risk factors of staff/volunteers and reassignment to protect workers;
  • Plan for staff/volunteer absences.
Are participants or event staff/volunteers from demographic groups at greater risk of severe disease, such as older adults or people with underlying medical conditions? Older adults, people with immune compromising conditions and chronic diseases appear to be at greater risk of severe disease, so consideration should be given to protecting them from possible exposure to COVID-19 cases.  Communication about risk to these participants should be emphasized. High importance
Are persons attending the event members of critical infrastructure roles, such as healthcare workers? If transmission occurs at the mass gathering, participants may be subject to self-isolation or may become cases themselves. This could lead to critical infrastructure disruptions/absenteeism if the participants at the event represent critical services and industries. High importance
Are participants members of a professional group that might have increased risk of infection? Healthcare workers may have greater risk of infection and therefore of infecting others due to the possibility of occupational exposure to COVID-19 cases. Participants who work in close contact with international travellers may also have increased risk. Medium importance
Are participants at greater risk of spreading the disease, such as young children? Young children may be at greater risk of amplifying disease transmission because they are generally less compliant with effective hand hygiene and respiratory etiquette practices and tend to socialize with others in a way that is likely to increase transmission. Consideration should be given to preventing children from spreading the disease. Medium importance
Are participants from areas where health system resources are limited (e.g. remote and isolated communities)? Event participants returning to communities with limited health system resources may introduce the virus to communities where there is less capacity to contain and mitigate spread. Medium importance
Are all participants registered, with available contact information? In the event of an outbreak associated with the event, contact information for the participants may be requested by public health for follow up and contact tracing. Medium importance
  • Maintain contact information for participants.
Local demographics  and epidemiology Is the local community experiencing ongoing transmission of COVID-19? Local community transmission can put mass gathering participants at risk of infection. In an affected area, other services for participants may be operating at limited capacity (e.g. restaurants, hotels, etc.). High importance
  • Involve relevant partners including local public health authorities.
Is the local population at increased risk of severe disease if COVID-19 circulated? Some communities may want to reduce their risk of importation of COVID-19 due to characteristics of the local community, such as a high number of elderly residents, or higher rates of chronic disease. Medium importance
Mass Gathering / Event
Event activities Will participants be participating in activities that promote transmission? Activities that could contribute to spread: greetings (handshakes, hugs, kisses), singing, cheering, close physical contact such as when participating in contact sports, sharing cups, dishes, utensils, etc. High importance
  • Offer virtual or live-streamed activities;
  • Provide packaged refreshments instead of a buffet.
Crowding Will participants be consistently within 2 metres of one another? Respiratory droplets tend to fall within 2 metres of their source, so maintaining a 2 metre distance from others is a precaution to prevent spread. High importance
  • Change the venue to prevent crowding.
Is the event being held indoors, outdoors or both? Events held outdoors may be lower risk for transmission of respiratory illness than those held indoors due to higher ventilation. Footnote1 Medium importance
  • Consider holding events outdoors or increasing ventilation by opening windows and doors (weather permitting).
Will there be restricted points of entrance and exit that force people to be in close proximity and/or pass through high-touch areas (e.g. doors and elevators)? Crowding and lines at bottlenecks can put participants at increased risk of exposure to respiratory droplets. High-touch surfaces can be contaminated and increase the risk of transmission. Medium importance
  • Stagger arrivals and departures.
  • Enhanced environmental cleaning and pay special attention to high touch surfaces.
Event duration How long will participants be gathered at the event? Longer events present more opportunities for transmission. Consider how overnight accommodations may affect crowding, proximity, and nature and duration of contact. Medium importance
  • Shorten events or stagger attendance.
Event resources Will hand hygiene stations be available throughout the venue? Hand hygiene will be performed more frequently if alcohol-based hand sanitizer or hand washing sinks with soap and disposable towels are readily available. Medium importance
  • Increase access to hand hygiene stations.
Can the event venue(s) be configured to reduce proximity between participants? Respiratory droplets tend to fall within 2 metres of their source, so maintaining a 2 metre distance from others is a precaution to prevent spread. Medium importance
  • Configure the venue to promote a 2 metre distance between participants
  • Locate space that can be used to isolate ill participants or workers
Will high-touch surfaces be cleaned and disinfected frequently during the event? High-touch surfaces can be contaminated and increase the risk of transmission. SARS-CoV-2 may live on surfaces for a few hours or up to a few days. It can be killed with store-bought disinfectants. (link to environmental cleaning Fact sheet) Medium importance
  • Increase frequency of cleaning of the environment and pay special attention to high touch surfaces. Use a product that cleans and disinfects
  • Ensure adequate staffing to maintain prevention strategies such as hand wash stations and regular cleaning and disinfection
Will there be health professionals or first responders at the event to screen and/or attend to someone who may be symptomatic? Although screening may not identify all participants with COVID-19, health professionals may be able to quickly identify and isolate symptomatic individuals from other participants. Health care professionals should be familiar with appropriate PPE and IPC measures. Low importance
  • Consider having health care professionals onsite to screen for or attend to people with symptoms
  • Ensure that prevention supplies and training for their use are available to staff/volunteers (e.g. personal protective equipment)
  • If  available, provide disposable medical masks for use if a worker or attendee becomes sick at the event
Health system capacity Does the local health system have the capacity to assess, test and care for persons suspected of COVID-19, potentially in large numbers? Persons under investigation and cases of COVID-19 could present a substantial burden to the local health system if many require testing and care in a short period of time. High importance
  • Communicate how to access local health care, including calling ahead to prevent exposure of others in the healthcare setting
Geographic location Is the location of the event geographically remote or in close proximity to a densely populated area? Geographic remoteness might limit access to tertiary care and may make it more difficult for a case to be repatriated.

However, proximity to a densely populated area could result in more rapid dissemination of disease.

Medium importance
  • Involve relevant partners including local public health authorities and emergency medical services
Table 1 Footnote 1
Public Health England. Impact of mass gatherings on an influenza pandemic: Scientific evidence base review. 2013. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/316200/Mass_Gatherings_evidence_Review.pdf

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Footnote 1
World Health Organization. Key Planning Recommendations for Mass Gatherings in the context of the current COVID-19 outbreak.  Feb 14 2020.  Available at:  https://apps.who.int/iris/bitstream/handle/10665/331004/WHO-2019-nCoV-POEmassgathering-2020.1-eng.pdf?sequence=1&isAllowed=y

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Footnote 2
United States Centers for Disease Control and Prevention.  Get Your Mass Gatherings or Large Community Events Ready for Coronavirus Disease 2019. Mar 3, 2020. Available at: https://www.cdc.gov/coronavirus/2019-ncov/community/large-events/mass-gatherings-ready-for-covid-19.html

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