Calgary’s COVID-19 transmission rate is 1.246. What does that mean?

Click to play video: 'Calgary sees increase in rate of transmission of COVID-19'
Calgary sees increase in rate of transmission of COVID-19
WATCH: Officials with the City of Calgary are keeping their eye on the R number -- otherwise known as the rate of transmission – as the COVID-19 pandemic drags on. As Adam MacVicar reports, it’s a number many would like to see as low as possible. – Sep 29, 2020

For every one Calgarian who gets COVID-19, they’re likely to infect, on average, more than one person, according to new data from the University of Calgary.

In a Tuesday tweet, Calgary Emergency Management Agency chief Tom Sampson said research shows the city’s rate of transmission of the novel coronavirus — or r value — is 1.246.

That means, according to Sampson, if 10 people in Calgary were to get COVID-19, they’d pass it on to an average of 12.46 people. Those people would then pass it on to 15.52 people, and those would pass it on to another 19.34 people.

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Sampson ended his tweet by saying #LetsStayOpen.

Sampson said the jump from a transmission rate of one to 1.2 is actually an increase of 20 per cent, so that number is very important for officials.

“I think the ideal transmission number is anything below one,” Sampson said. “Which means, essentially, over a period of time, it’s going away and you’re not impacted by COVID-19 in a major way. Anything consistently below one is an improvement.”

Transmission increase ‘directly attributable to our behaviour’

According to Dr. Craig Jenne, a University of Calgary associate professor of microbiology immunology and infectious diseases, any number that’s over one means the virus will continue to spread.

Jenne said the transmission rate is “directly attributable to our behaviour” when it comes to adhering to health measures meant to limit the spread, as the virus has not changed and people have not become more easily infectible.

“We are now gathering in larger groups, we’re doing more things indoors, whether that be, for example, sports… but also school and work, and the more times we get together in an indoor environment, the more likely there is viral transmission,” he said.

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“I think it is a level of which we maybe need to have a little concern. If it continues to increase, it could get very bad.”

Click to play video: '1 million Albertans have been tested for COVID-19: Health Minister'
1 million Albertans have been tested for COVID-19: Health Minister

Jenne said increasing case numbers could put a strain on testing, especially with flu season fast approaching, which means people need to keep up with basic rules like washing their hands, staying home when feeling sick, physical distancing and wearing masks.

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“We need to ensure that people can get tested in a timely fashion so we don’t want to keep adding more and more cases to an already sort of maximized testing system,” he said.

Other cities seeing lockdowns, tightened restrictions

Calgary is still “outperforming” other large cities across the country, Jenne said, as some cities and provinces experience a “second wave” of the COVID-19 pandemic and have returned to restrictions and lockdown measures.

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In Quebec, a 28-day partial lockdown was announced for Montreal on Monday after the city shifted into a red alert level due to the numbers.

On Tuesday, Ontario Premier Doug Ford said the province was officially in its second wave after 700 new cases of COVID-19 on Monday — the highest single-day increase the province has seen since the start of the pandemic.

Last week, Alberta chief medical officer of health Dr. Deena Hinshaw said she doesn’t believe the province is experiencing a second wave, despite an uptick in case numbers, because “the concept of a second wave implies that we don’t have any control or influence over the circulation of the virus.”

“We have seen increased daily case counts for the last few months but those have remained relatively stable,” Hinshaw said at the time. “And when I think about a second wave, I think about a very large spike of uncontrolled spread.”

Click to play video: 'Hinshaw does not think Alberta is in a second COVID-19 wave'
Hinshaw does not think Alberta is in a second COVID-19 wave

Jenne agrees, saying that Alberta has the testing and hospital capacity to accommodate the current steady increase.

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“That being said though… we are seeing — again — increased cases, and unfortunately, these things can amplify,” he said.

“So what may be a controlled, small increase now could seed broader and wider-spread virus in the future, so we do still have to be cautious. We have to be vigilant.”

As it stands now, Jenne said he doesn’t see a need for added restrictions in the city, but if the cases continue to grow, officials might want to look at implementing targeted reductions.

Sampson said that “Calgarians have done a great job” when it comes to responding to rising case numbers and working to bring those numbers down.

He said seeing the situations in other provinces makes him nervous.

“We don’t want to follow them,” Sampson said. “It’s just so fundamental to the well-being of the businesses in our community, the well-being of our people in the community.”

Jenne also stressed that decisions on restrictions and increased precautions are made with consideration of more than just transmission rates, including things like hospitalization and ICU admission rates.

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Tyler Williamson, associate director for the Centre of Health Informatics at the University of Calgary, said the rate of transmission has been cyclical throughout the pandemic but the recent numbers show a more consistent trend.

“We’ve seen that it’s normalized a bit, that the rate of transmission has slowed,” Williamson said. “It’s consistent with what I’m seeing in society as I go out and buy groceries like everybody else. We’ve kind of all settled into our way of being.”

Williamson is part of the team researching the data that is sent to the City of Calgary.

He said many of the large spikes in the transmission rate throughout the pandemic have been due to larger outbreaks in the Calgary area.

While Williamson believes Calgarians have been doing a good job in handling the spread of COVID-19, there is still much to be learned from the data as it comes in.

“When we really start to worry is when the confidence interval gets fully above one — that means it’s statistically above one,” Williams said.

“If we can keep the confidence interval on one, we may be above but we may also be slightly below.”

– With files from Global News’ Adam MacVicar


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