Why contact tracing becomes 'impossible' as coronavirus cases surge

WATCH: Toronto COVID-19 cases rising at a rate that could ‘outpace’ contact tracing efforts, top doctor says.

The city of Toronto is rolling back its contact tracing efforts as the city grapples with a backlog of coronavirus infections. The cases are rising so rapidly that contact tracing just isn’t possible now, experts say.

Although contact tracing is effective in combatting the spread of the virus, when cases start rising, it becomes difficult to implement unless there are proper resources.

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“At its core, (contact tracing) absolutely works,” said Alon Vaisman, an infectious disease and infection control physician at the University Health Network in Toronto. “But you need the resources and to do it quickly. If you can’t do it within a 24-40 hour window, it becomes almost impossible.”

Contact tracing is a way to track down people who might be infectious and keep them away from others. It can break the chain of coronavirus transmission and help prevent outbreaks. The World Health Organization called it an “essential public health tool for controlling the virus.”

The idea is to try and find the infected person before they infect others and stop the “next generation of COVID-19 cases,” Ashleigh Tuite, an epidemiologist at the University of Toronto, said.

“But you have to do it quickly as the virus spreads relatively quickly,” she said.

“It’s a race against the virus.”

And if health departments don’t have enough contact tracers (people trained to call up those who tested positive for COVID-19 and gather information), then it could be a losing battle.

“Eventually it becomes impossible to keep up,” she Tuite said.

This is what happened in Toronto last week.

On Oct. 4, Toronto Public Health announced it was scaling back its contact tracing efforts as the city is struggling with a “high level” of infections. Instead, it said the city will be focusing its tracing efforts on high-risk scenarios, like schools and long-term care homes.

“As part of the usual course of outbreak management, when cases reach a high level, public health must make a strategic shift and temporarily re-prioritize case and contact management to focus on the highest-risk scenarios,” Toronto’s medical officer of health, Dr. Eileen de Villa, said.

She said there are 700 contact tracers in Toronto, the highest in the country, but infection rates are rising so rapidly that it is outpacing contact tracing, “no matter how many people are deployed for this.”

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“I expect we could have 700 people added to the ranks and still be unable to contact trace with the same reach and results when infections were lower,” she said, adding that she expects Toronto will go back to regular contact tracing as soon as the COVID-19 cases start going down again.

Vaisman said Toronto’s decision to rollback on contact tracing, “makes sense,” considering the city’s limited resources.

“In an ideal world, we would have enough contact tracing calls every day to get to all the cases,” he said. “But the problem is resources and money, it’s as simple as that. If you have the resources, contact tracing is very important. But if you don’t, then I think it is the right decision to transfer the resources to other settings, like vulnerable people.”

He added that with contact tracing, “you do it well or you don’t do it at all.”

But there are more resources coming to Ontario, which could help with the backlog.

On Tuesday, Ontario Premier Doug Ford said the province is investing $1.3 billion on COVID-19 testing and contact tracing through its fall preparedness plan in order to reduce backlogs and build the province’s testing capacity.

2nd wave contact tracing is different

During the first wave of the pandemic in March, contact tracing was used and worked well, Vaisman said.

But there is a key difference between March and now, he said. In the spring, the average person who was getting infected with the virus was older. And stores, restaurants and gyms were also shut down, so people weren’t able to get out as much, he added.

During the second wave, the average person getting infected with the virus is now typically younger and more socially mobile, Vaisman said, adding that stores, restaurants and gyms are also still open, contributing to the spread.

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So instead of contacting one or two people, you may have to contact 1,000 people in a day. And without the resources to do that in a timely manner, he said, then the cases end up spreading.

Tuite said provinces in Atlantic Canada, that have relatively low COVID-19 cases, have been able to successfully use contact tracing techniques.

For example, since Oct.1, Nova Scotia has had one confirmed case of coronavirus. Ontario has had more than 2,000 reported cases since the beginning of the month and Quebec has had more than 7,500 reported cases.

The more COVID-19 cases there are, like in Ontario and Quebec, the more contact tracers you need.

“But we have a limited pool of contact tracers, and eventually you have to say ‘we can’t keep up anymore’ and we’re going to have to prioritize and focus on long-term care homes or schools instead. Sort of like triage,” Tuite explained.

Vaisman said there is technology to help, such as Canada’s national tracing app. But there are glitches to this.

The app does not work in the sense of traditional contact tracing. It notifies people based on proximity to an individual who has informed the app of a positive coronavirus test result.

The app is also voluntary as there’s no requirement for anyone who does test positive to log that information so as to alert others of potential exposures. The technology also has not been rolled out in every province yet.

‘Full-blown lockdown’

Contact tracing isn’t the only problem provinces like Ontario and Quebec are facing.

There are also issues with testing as it takes time to get a COVID-19 result back — sometimes days. Another issue is getting a test done, as line ups continue to grow at sites across the country.

Vaisman said when you put these three problems together — contact tracing difficulties, long lines to get tested and a backlog in results — then another lockdown seems “inevitable.”

READ MORE: Indoor dining, gyms ordered to close in Toronto, Peel Region and Ottawa amid coronavirus pandemic

“The consequences of not being able to do contact tracing is that nobody knows what going on. We have a rough idea, but no one really knows who was in contact with who. If you don’t have the resources to improve contact tracing, then all you can do it shut everything down. A full-blown lockdown.”

Tuite agreed.

She said if contact tracing isn’t possible and the province needs to get the COVID-19 numbers down, then restricting contacts is another option.

“This is where we are now. There are too many cases and testing and tracing aren’t working. So we need to start shutting down bars and restaurants again to get the cases back to a manageable level,” she said.

On Friday, Ontario announced it was implementing restrictions in Toronto and Ottawa to help stop the spread of the virus.

The new measures, which are set to take effect on Saturday at 12:01 a.m., include the closure of indoor dining at restaurants and bars, as well as the closure of gyms, casinos, cinemas, and performing arts centres.

© 2020 Global News, a division of Corus Entertainment Inc.

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