Social distancing and why it works, explained by math Professor Jane Heffernan

Social distancing: It's a term that has become a buzzword associated with the global pandemic of the novel coronavirus causing COVID-19. It saturates the news, social media, our conversations with family, friends and neighbours. Some of us have become watchdogs of social distancing, monitoring our neighborhoods and hoping for it to happen in abundance; others of us have taken to spreading the call-to-action on social distancing in an effort to curb the spread of the virus. Many of us are realizing how, on days before the pandemic, we never really monitored the distance between ourselves and others.

Stay six feet apart (that's two metres, for the metric-minded), and don't gather in groups. That's what Canadians have been asked to do.

But what does it mean from a mathematical lens? What is the mathematical evidence that shows social distancing to be effective in curbing this outbreak?

Jane Heffernan

York University Faculty of Science Professor Jane Heffernan says keeping a specific physical distance away from others does prevent the spread of the virus – that can be expelled by cough, sneeze and breathing – by creating a spatial barrier from an infected person.

Heffernan, a professor in the Department of Mathematics and Statistics, York Research Chair (Tier II), and communications director of the Centre for Disease Modelling (CDM), says the math shows that social distancing can indeed stop a chain of exposures.

"Someone can infect a person, and then that person can infect someone else, and so on… but if one person is social distancing in this chain, all of the possible infections that come after them will not happen," she said.

Ontario, and Canada, have been taking proactive steps to undertake and promote social distancing, but different organizations and institutions are approaching this with different measures and timelines. In order for it to have the greatest effect on "flattening the curve," Heffernan says we should be engaging now, and remain diligent not to allow our social distancing behaviour to wane.

"If it does wane," she says, "we will not be able to control transmission effectively. Additionally, we must keep up our social distancing behaviours until we are told that we are allowed to decrease them. If we decrease our behaviours too early, it is possible that we can bring on a second wave of infection."

An image of the COVID-19 virus (Image: CDC)

An image of the COVID-19 virus (Image: CDC)

The challenges then become maintaining the behavior – and complying for as long as it takes. This may seem like a daunting task given all that is still unknown about the virus. For instance, we don't actually know where we sit on the "curve," and Heffernan agrees it is too early to predict when the peak in Ontario will happen.

"I don’t expect to see a peak in the short term. There is a lot of uncertainty in data right now, so peak projection times from models have a broad range. Shorter estimates are a month. Longer estimates are a few months," she said.

The provincial government recently announced that it will extend the school closures beyond the initial two-week closure, and school-aged children won't be back in the classroom on April 6. Heffernan agrees this is the right approach; however, how long the schools stay shuttered remains to be seen.

Based on her own research on social distancing, Heffernan says the more diligent people are in adhering to social distancing measures now – even though it may feel disruptive – the shorter the time frame will be that we need to adhere to them.

"Sometimes it is hard to adhere when the infection is not ‘observed’ as being ‘close’ to a person. We must all remember that our behaviour affects not only those ‘close’ to us, but all of the other people that would be down a chain of infections," she said.

Heffernan's research shows that not only does social distancing slow the spread of disease, it also decreases the infection burden on the healthcare system. It also shows that when social distancing behaviours begin to wane – near the end of an epidemic – this poses a great risk for a second wave of the infection.

"We MUST be diligent in our social distancing behaviours until we know we are allowed to relax them," she said. "It's best to keep your circle very small for now."

By Ashley Goodfellow Craig, deputy editor, YFile

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