Chennai: By looking at factors such as transmission intensity, duration of exposure, the proximity of individuals and degree of mixing- Simon Fraser University professors Paul Tupper and Caroline Colijn, have developed a model to test the effectiveness of anti-Covid measures such as physical distancing, masks or social bubbles when used in various settings.
According to the findings, physical distancing is universally effective at reducing the spread of the disease, while social bubbles and masks are more situation-dependent.
They introduced the concept of āevent Rā, which is the expected number of people who become infected with Covid-19 from one individual at an event.
The researchers incorporated data from reports of outbreaks at a range of events, such as parties, meals, nightclubs, public transit and restaurants. They say that an individual’s chances of becoming infected with Covid-19 depend heavily on the transmission rate and the durationāthe amount of time spent in a particular setting.
Events were categorised as saturating (high transmission probability) or linear (low transmission probability). Examples of high transmission settings include bars, nightclubs and overcrowded workplaces while low transmission settings include public transit with masks, distancing in restaurants and outdoor activities.
The study that has been published in the journal, Proceedings of the National Academy of Sciences of the United States of America (PNAS), suggests that physical distancing was effective at reducing Covid-19 transmission in all settings, but, the effectiveness of social bubbles depends on whether chances of transmission are high or low.
In settings where there is mixing and the probability of transmission is high, such as crowded indoor workplaces, bars and nightclubs and high schools, having strict social bubbles can help reduce the spread of COVID-19.
The researchers found that social bubbles are less effective in low transmission settings or activities where there is mixing, such as engaging in outdoor activities, working in spaced offices or travelling on public transportation wearing masks.
They note that masks and other physical barriers may be less effective in saturating, high transmission settings (parties, choirs, restaurant kitchens, crowded offices, nightclubs and bars) because even if masks halve the transmission rates that may not have much impact on the transmission probability (and so on the number of infections).