Table 3.

Community practice as preventive measure—risk; behavioural change; health co-benefits; enabling and limiting factors and strength of evidence

	Avoid crowds and mass gatherings	Avoid travel
Risk	• Crowded areas with unknown people are considered high risk due to risk of droplet transmission and infection through contaminated surfaces • Talking can potentially result in respiratory infectious disease transmission108 • Possibility of transmission by asymptomatic carriers within a crowd increases risk109	• Travelling to areas with confirmed cases will increase an individual’s risk of potential exposure to COVID-19 • The stability of the virus on surfaces,20 the potential prevalence of asymptomatic carriers,109 the difficulty and lack of distancing,110 shared toilets and risk of toilet plume86 and uncertain travel history of others make environments. such as trains and aeroplanes, challenging in terms of protection and high risk in terms of COVID-19 transmission
Behavioural change	• Observe social distancing measures4,19,25,32–34,42,78,111 • A separation of 1 m is the minimum as recommended by the WHO.41 Although most droplets may not travel across this distance, novel studies exploring the influence of aerodynamics112 as well as the potential for sneezes to travel up to 8 m80 have led to the recommendation that possible distancing should be maintained wherever possible • Avoid congregating and take precaution when in public areas such as parks, cinemas and restaurants. These areas should make face mask wearing mandatory, carry out temperature checks, limit the number of people in attendance and practice distancing of people	• Avoid travelling to areas with confirmed cases, which are of significant risk25,33,34 • Take all necessary personal protective measures such as wearing of face masks, eye googles, disinfecting immediate area with alcohol-based solution and avoiding food sharing • Implementing (for authorities) appropriate protective measures such as mandatory temperature checks prior to travel and/or upon arrival, reporting the travel and medical history of each traveller and distancing requirements on transport
Co-benefit(s)	• Reduced outdoor pollution due to minimized outdoor human activity.113,114 Lower exposure to outdoor air pollution, which causes respiratory illnesses such as lung cancer and contributes to mortality60,115	• Reduction of cross-border transmission111 • Improved general hygiene on transport such as trains or aeroplanes • Environmental benefit from reduced air-travel carbon footprint116
Enabling factor(s)	• Ability to avoid crowded areas as permissible by population density, occupation, religion or culture	• Ability to make decisions on when or how to travel
Limiting factor(s) and/or alternative(s)	• Crowded areas may not be avoidable due to occupation, religious necessities or otherwise. Where gathering is necessary, individuals should take personal responsibility to wear masks, keep hands clean and maintain maximum distance from others	• Access to facemasks, goggles or alcohol-based solution for personal protection during travel • The necessity of travel, for personal or professional reasons, such as pilots and the cabin crew
Strength of evidence	• Studies on influenza and COVID-19117 indicate a potential role of mass gathering reduction in limiting transmission,118 though studies are limited and not yet conclusive • There are also studies on the elevated transmission of other viruses as a result of mass gatherings119–121	• The proximity and contact with individuals heighten the evidenced risk of taking in potential respiratory droplets containing COVID-19 from others • There is no clear evidence regarding increased risk from aeroplane travel specifically