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Canada's COVID-19 infections skew younger than anticipated

JODOIGNE, BELGIUM - APRIL 1 : Illustration picture in a local bio grocery. The federal government placed a lockdown to stop the spreading of Covid-19. Schools are closed and lessons are suspended as well as restaurants, cafes and bars due to the outbreak of COVID-19. Pictured on April 01, 2020 in Jodoigne, Belgium, 1/04/2020 ( Photo by Vincent Kalut / Photonews via Getty Images)
More young people may be affected by COVID-19 than originally thought. ( Photo by Vincent Kalut / Photonews via Getty Images)

In Canada, the latest numbers on COVID-19 show that it’s hitting a demographic younger than originally anticipated.

The highest proportion of cases in Canada appear to be people ages 40-59 (37 per cent), followed by those 20-39 years of age (29 per cent) and 60-79 years of age (25 per cent). Only a small proportion of cases (four per cent) have been reported among people under the age of 19.

The numbers don’t reflect what many had expected when the pandemic was declared — that seniors would be the ones most affected.

Earl Brown, emeritus professor of virology at the University of Ottawa, says the numbers could reflect those who were active in the community, and therefore more at risk of picking up the virus. In Italy, where it is common for several generations to live in one household, a higher percentage of elderly were infected with the disease.

“There was a lot of transfer from people who were out and about and brought it home to the elderly,” he tells Yahoo Canada. “It’s good news when the older people aren’t infected because they’re the ones with the worst outcomes. The ones who are being infected are more resistant to dying.”

In Canada, there’s been more awareness about the risk of spreading the virus, and as a result, we’ve been swift to self-isolate.

“Now the spread is a bit more limited and it seems to be more the younger groups,” says Brown. “It’s more the opportunity of who gets infected than who had the opportunity to get infected.”

He adds that Germany seems to be faring well as a nation, as it has a low mortality rate, and a higher rate of younger people who are being infected with the virus.

Limits on accuracy of demographic information

Matthew Oughton, an assistant professor in the department of medicine at McGill University, says it’s important to remember that the numbers only reflect those who have been tested.

“If you don’t take a temperature, you don’t find a fever,” he says. “These numbers aren’t telling us about the people who aren’t being tested.”

Scientists are only going to understand the true behaviour of COVID-19, such as the distribution and who is affected, after the fact.

“Only in retrospect can you apply a single, uniform definition, and you have all the data you need,” he says. “Right now, this is a moving target.”

The current testing data is based more on the severity of the disease, rather than its prevalence.

“There may be a whole bunch of people who have this disease but aren’t sick with it,” Oughton says. “Hence the public recommendations for people to physically distance.”

Once the pandemic is over, there will be large population-based studies that examine who had the disease and the different levels of severity.

“That’s how we’re going to know the truth but we’re probably a few months away from that kind of data,” says Oughton.