Coronavirus: Explaining the need for social distancing using ping pong balls

Coronavirus: Explaining the need for social distancing using ping pong balls
Copyright Witteman Lab, Canada
By Seana Davis
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Experts have been getting creative in trying to explain how contagious COVID-19 is and why it is important to practice social distancing.


Newly released research suggests coronavirus could be twice as contagious as previously thought.

It comes as Europeans are being urged to continue to practice social distancing to stop the spread of COVID-19. But, without understanding how the disease spreads, warnings such as these may fall on deaf ears.

Among those trying to explain the need for social distancing are health authorities and engineers, who have created videos, gifs and apps in a bid to get the message across.

Breaking down the numbers using ping pong balls

The Ohio Department of Health released this video that quickly went viral, using ping pong balls and mouse traps to illustrate social distancing.

One ping pong ball can set off a chain of events leading to throngs of released mouse traps. If the ping pong balls are spaced out, then less of the mouse traps are set off, therefore flattening the curve of growth.

Ohio Department of Health

How contagious a virus is can be narrowed down to one equation, R naught. This number details how infectious a virus is and can provide an approximation of the amount of new people an existing case can infect. If a number is less than one, then someone with the infection will spread the virus to fewer than one person. If R naught equates to five, then one person will transmit the virus to five others, on average. Then the next 5 people can infect 5 others, rising quickly to exponential growth.

The equation can be complex and relies on numerous external variables that are outside of our control, such as how deadly the virus is, and can fluctuate. Some of those parameters include the incubation of the virus, and the infection period.

But according to new research - from the US Centers for Disease Control and Prevention - suggesting coronavirus is more contagious than previously thought, R equates to 5.7 in a 95% confidence interval. Although this data only looks at information from within China, if this R naught figure relates to global contagiousness then one person can infect six and so on. Using the ping pong balls as an analogy, then one ping pong ball would hit six on average each time, rather than the 2.5 previously estimated. After six cycles of this, nearly 10,000 balls will have been affected. After 10 cycles, 12,093,235 ping pong balls will have been thrusted off the mouse traps.

There is a difference when calculating the exponential function of a pandemic - for example, the amount of time that passes is a key element. However, both exponential functions can change course - if social distancing is maintained - or the mouse traps move aside

The study, released on April 8, states that "active surveillance, contact tracing, quarantine, and early strong social distancing efforts are needed to stop transmission of the virus". The separation of the ping pong balls, or maintaining our social distance, remains to be an element that we have control over.

An app that uses avatars to make it personal

Others, like Associate Professor Holly Witteman and a team of PhD students have created an app and a gif to demonstrate how effective social distancing can be, and to make it personal.

"The mathematics between how infectious disease spreads is not always immediately apparent to everyone. Some people understand it right away and for other people, it is a more challenging concept," Dr Witteman, who is the Canada Research Chair in Human-Centred Digital Health at Laval University in Quebec, told Euronews.

The app allows the user to create avatars, or graphical characters, to be a part of the community.

"We had never seen anything where it was made really personal," Dr Witteman said. The aim of the project is to allow people to visualise how the process of social distancing applies to them and the people around them.

Dr Witteman's research focuses on "how to explain complex concepts to people about health. Especially things that involve numbers," she said. "What we are doing is taking existing mathematical models and showing what that could mean in a community".

Has social distancing worked yet?

Mathematical epidemiologists have been sharing research via social media with regards to social distancing, with some pointing to positive signs within countries like Austria and the United Kingdom - the data being consistent with the lowering of social interactions.

One of the key questions that many have is what will happen once the peak is reached. Once social distancing measures are relaxed, and the ping pong balls are brought together once more, policy makers and scientists alike will be grappling with how to ensure a mouse trap won't be released, causing a second wave.

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