It’s easy to assume that if influenza could be transmitted within the home, at school and at work, that the risk is exponential at a sports event or festival. Evidence has shown us that if restrictions on mass gatherings are implemented early on in pandemic, alongside other social distancing measures, can greatly reduce the risk of transmission. However, research conducted into virus transmission at mass gatherings is showing that there is varied evidence in the association of size with the transmission of influenza (Ishola and Phin, 2011). In the current climate, the banning of events seems to be based on size rather than any other factor, but is this the appropriate metric to measure? Is the risk of transmission greatly reduced by banning an event over 1,000 people but allowing one with 999 to go ahead?
Density and Duration
Reducing density and shortening duration at an event reduces the risk of transmission.
Research into public health at mass gatherings shows that it appears the type of event is key in assessing the level of risk to spreading influenza (Ishola and Phin, 2011). Events with high crowd densities (estimated at 5 or more per square metre) and where people lived close together for prolonged periods, for example, Hajj pilgrimage and large music festivals, displayed high rates of transmission (Memish et al, 2015). The authors even claim that the size of the event does not seem to be a critical factor. The higher transmission rates seem to be where contact continues outside of the event venue, such as accommodation; and events with campsites usually have sub-optimal hygiene facilities.
Reducing density is usually the first policy implemented as we already know that social distancing works. Evidence tells us that cities implementing rapid and strict non-pharmaceutical measures including social distancing early on in a pandemic, recover quicker than cities that don’t (Correia et al, 2020). Reducing density and shortening duration at an event reduces the risk of transmission.