In Canada, physical-distancing recommendations amid the coronavirus pandemic are pegged at two metres.
In the United States, it’s 1.8 metres. In Italy and Germany, it’s 1.5 metres. China and France have gone with just one.
The World Health Organization recommends maintaining a minimum of one metre apart from others during the COVID-19 pandemic, but physical-distancing guidelines vary slightly around the world. Numerous studies have found that people standing less than one metre away from an infected person were much more likely to catch the virus than those standing more than one metre away.
Britain is the first to consider reducing that measurement, hinged on the country’s plan to enter the second stage of reopening on July 4 when bars and restaurants can open doors.
While reducing the two-metre rule to one metre isn’t “totally unscientific or unfounded,” it comes with increased risk, said Raywat Deonandan, an epidemiologist at the University of Ottawa.
“It appears to be a balancing of the need to keep people safe against the need to have large numbers of people moving through society,” he said.
But, he noted, it’s not all about distance.
“It’s also about duration and intensity,” he said. “I’m much more comfortable passing someone on the street a half metre apart than I am having an extended conversation with someone two metres away.”
Scientists agree that COVID-19 infections typically happen when a healthy person comes into contact with respiratory droplets from an infected person’s cough, sneeze or breath. The droplets tend to fall to the ground within one to two metres of the person who emits them.
Two-metre rule not ‘hard science’
That’s why the two-metre rule is the rule of thumb, said Colin Furness, an infection control epidemiologist and assistant professor at the University of Toronto, but even then, it’s not “hard science.”
Some research suggests droplets of all sizes can travel seven to eight metres, while others suggest the virus particles can persist in the air in aerosol form. It’s prompted some scientists to argue that staying father than two metres apart would be better.
“Our understanding of transmission dynamics is really weak. Our best understanding is that when someone sneezes or coughs, droplets can go about one metre, but that’s probabilistic. In other words, the sneeze doesn’t know to stop at the one-metre zone, but for the most part, it’s a metre,” Furness said.
“The best evidence we have, overall, says that two metres is good, safe and smart.”
Canada, so far, agrees. At a federal level, Canada is one of only a few countries that has recommended the two-metre physical-distancing rule, along with Spain and the U.K.
Lowering the distance people have to keep from one another isn’t in the cards for Canada at this point.
Chief public health officer Dr. Theresa Tam acknowledged that there’s still much to learn about the virus and that guidelines will be adjusted accordingly as more evidence is reviewed.
The current approach is “multi-faceted,” she said, and is only successful within the context of other recommendations like wearing masks and staying home if you’re sick.
“The bottom line is — one metre can help avoid some of those droplets, but two metres will be better,” she told reporters Monday. “Some of it is about feasibility in certain settings. It’s a matter of a risk assessment approach.”
As more data comes in, Deonandan said he wouldn’t be surprised if Canada revisits the distancing guidelines. He said what happens in Britain could be a lesson.
“A lot of this is ‘the art of the possible.’ What is possible for us to implement in Canada?” he said.
“Three metres is better than two, but keeping people three metres apart is not realistic. Similarly, two metres is better than one, and so far it’s been possible for most of Canada to comply, but there are some denser areas where one metre is simply all we can implement. This might become more the case as more of the economy opens up.”
Combining masks with distancing
The concept of physical distancing is “messy,’ Furness said, and only becomes messier as provinces make their own unique moves to reopen.
Quebec announced it would reduce physical distancing requirements for children 16 and under to 1.5 metres, including places like day camps and schools, starting June 22. Children under 16, however, will still need to keep a two-metre distance from adults, such as their teachers. Other provinces, like Ontario, have expanded limit gatherings from five to 10 in recent weeks.
Keeping a fair distance is still a part of all loosening guidelines in Canada.
“But the two metres, by itself, doesn’t actually make a huge difference,” Furness said. “Actually, what you want is a combination. You want the mask and the distancing.”
Experts, like Tam, agree that the distancing recommendations go along with mask-wearing.
National public health guidelines were updated in May to recommend wearing a mask when it is not possible to “consistently maintain” a two-metre distance from others, particularly in crowded public settings like stores and public transportation. The recommendations are just that — recommendations. Wearing a mask in public has not been mandated in Canada, despite growing calls from doctors, such as a group in Ontario, to do so.
Furness also believes masks should be mandated.
“But it brings up important questions: are the two suitable for each other? Does a mask make up for distance? Does distance make up for a mask?” he asked. “We don’t know. Science doesn’t know yet. But the best understanding is that we want both.”
Tim Sly, an epidemiologist and professor emeritus at Ryerson University’s School of Public Health, said it’s a “sliding scale.”
“There’s no immediate cut-off at two-metres when everything suddenly changes from safe to unsafe,” he said. “One metre is better than hugging a stranger, especially when no masks are used.”
Peeling back layers of protections — like reducing distancing measures or allowing people back into office spaces, for example — is “inevitable,” Sly said.
“The flattening of the curve in Canada is due to the restrictions first installed being successful, but that doesn’t mean the risk has decreased when we pull back on how far apart people should stay, he said.
“It’s one of those decisions that society has to make,” he said. “How much? And at what cost? The answer is going to be different in different areas.”
— with files from the Canadian Press and the Associated Press