COVID-19 testing must become more widespread to prevent 'super spreader' events, experts say

With testing numbers low across Ontario and the highly contagious delta variant an ongoing threat, experts are urging the public to get swabbed more routinely or risk super spreader events.

Last Friday was the only day this month that labs processed more than 30,000 tests, according to provincial data. The all-time high for testing was on Jan. 15, when more than 76,000 tests were completed.

Meanwhile, the number of new COVID-19 cases has steadily increased this month, hitting 643 on Monday.

Toronto's Associate Medical Officer of Health Dr. Vinita Dubey said high testing rates are central to successful contact tracing, and is urging people who may be experiencing mild symptoms to get tested, even if they're vaccinated.

"That's probably one of our biggest categories to ensure that we catch all of COVID," Dubey told CBC News.

People also need to get tested if they've been in contact with someone contagious, or work where there's been an outbreak, she said.

Young adult cases high

Young adults should be extra cautious, Dubey said. They're more likely to go "out and about" to events, restaurants and nightclubs, increasing their chances of becoming infected with and spreading COVID-19.

Twenty-to-29-year-olds make up 23 per cent of the city's COVID-19 cases, the largest proportion of any age group, followed by 30-to-39-year-olds, according to city data.

Outbreaks have shifted from long-term care and child-care centres — where people wear masks and keep their distance — to restaurants, workplaces and the community, Dubey said. For example, Toronto restaurants Harbour 60 and Regulars both had outbreaks this month, according to Toronto Public Health.

In Hamilton, a large outbreak was declared at a nightclub earlier this month and has grown to 51 cases as of Monday. Public health officials say some patrons weren't wearing masks or physically distancing indoors. The city didn't answer questions from CBC News about the patrons' vaccination status.

Last week, the Durham Region Health Department reported an outbreak at an Oshawa basketball tournament, which was attended by 7,000 people. It has identified at least 25 people who were infected from Ontario and Quebec, but said officials were having difficulties getting in touch with all players and spectators.

Both outbreaks exemplify how fast the delta variant can spread compared to other strains of the novel coronavirus and the need for more testing to contain it, said Colin Furness, an infection control epidemiologist with the University of Toronto.

For over a year, he's been advocating for widespread testing, whether it be through widely available rapid tests, routine tests for staff or preemptive surveillance testing.

"When you have a large gathering, especially people coming from various different places that will then disperse again, that's got super spreader written all over it," he said.

"So if you're going to do that, first of all, ideally, everyone would be vaccinated and there would be proof of that. Number two, yes, there would be a rapid test before going out on the court or before going into the locker rooms, before that exposure."

Dubey said rapid tests are useful as a screening tool, but if people believes they have COVID, they should get a PCR (polymerase chain reaction) test done at a lab — whether they tested positive or negative on their rapid test.

PCR tests are the "gold standard" of COVID tests, Dubey said.

She's hoping testing becomes more routine as children head back to school. Toronto schools will send students home with saliva-based testing kits so parents don't have to worry about booking appointments if they suspect their child has been exposed to COVID-19.