Behind every known case of COVID-19 is a public health investigator working meticulously to figure out its origin and track its spread. Known as contact tracers, these specially trained sleuths make up the crucial intelligence arm of the battle to contain the virus.

But are there enough of them?

With more than 14,000 known coronavirus cases in Canada, some public health departments are concerned the workload could become too much. And in the search for ways to find and train more individuals to do the work, some are looking to Alberta.

There are now 70 contact tracers working at any given time in the province — a six-fold increase to the usual staff, who in normal times track the spread of other diseases, such as measles.

Working in call centre-style offices and spaced apart by the two metres advised by health authorities to prevent the spread of COVID-19, the new recruits include medical students from the University of Calgary and the University of Alberta.

While contact tracing is usually done by public health nurses, medical students have similar clinical experience, making them easy to train. In the past few weeks, more than 300 new staff have been taught the basics on how to work the phones by Richelle Schindler of Alberta Health Services.

Contact tracing is "one of the best ways to contain this virus," she says.

"South Korea, Japan, Singapore — they've all been able to contain the spread of this virus through aggressive contact tracing."

In Calgary, newly trained medical students are helping public health professionals connect with COVID-19 patients and track down anyone they may have inadvertently exposed to the virus. (University of Calgary)

Indeed Singapore, which has been lauded for its COVID-19 containment efforts, has teams of contact tracers working alongside the police department to enforce the isolation of anyone who has had contact with an infected person. Though the city-state of around 6 million people confirmed its first coronavirus case in late January, it has so far seen fewer deaths than Canada, and some commerce remains open due in large part to those measures.

Here in Canada, where such strict surveillance by authorities would likely prove controversial, the tracing process is designed to track down and alert those who may have contracted the virus, and ask them to self-isolate.

It begins when someone tests positive for COVID-19. A contact tracer will call the patient and ask them a series of questions in order to piece together their recent movements — from interactions with family members, to doctor visits, rideshares, and of course, air travel.

"It's very difficult, nuanced work, but very important," says Jennifer Nuzzo, an epidemiologist with Johns Hopkins University.

Though contact tracers are trained to suss out personal details, the 14-day incubation period for COVID-19 means infected patients have to recall their schedules and interactions from days or even weeks before.

"If you can imagine in your own life — or at least in your pre-lockdown life — how many people you may have come in contact with, that could potentially be a lot," Nuzzo says.

Sometimes, she adds, people may just not be willing to provide information to someone they don't know. Occasionally, that means making calls elsewhere to find out more.

For the team in Alberta, Schindler says the biggest hurdle is that people don't always answer the phone. But even facing these challenges, her team is currently managing to get through the province's entire caseload of COVID-19 patients — around 60 cases a day, at the time of writing.

"We are definitely not maxed out. We can do more," Schindler says.

Richelle Schindler of Alberta Health Services tells CBC's Adrienne Arsenault that the province has found a way to boost its contact tracing capabilities to keep pace with demand. 0:32

But even places that have lots of contact tracers can run into problems.

In Toronto, where cases of COVID-19 have increased by more than 500 per cent in the past two weeks, an office where Toronto Public Health contact tracers work was forced to evacuate after eight people there contracted the virus. Staff then had to perform contact tracing for the cases in their own building.

Dr. Vinita Dubey, Toronto's Associate Medical Officer of Health, said in an email that most of the city's 100 contact tracers are now working from home. Going forward, she wrote, the city will consider adding medical students or volunteers to their ranks, if necessary.

Ontario announced Friday that it is scaling up the contact tracing ability of public health agencies across the province, in part by hiring medical students.

In a press conference earlier this week, Chief Public Health Officer Dr. Theresa Tam said the federal government has heard from public health agencies in some parts of the country that are concerned they may soon become overwhelmed, should the spread of the virus outpace their ability to track it. Citing the successful program in Alberta, Dr. Tam said they are also recruiting students at the federal level in order to help provinces fill any needed contact-tracing positions.

Nuzzo says the need for contact tracers is likely to continue to increase, even as overall COVID-19 cases eventually start to level off. She says physical distancing measures alone aren't going to be enough to stop the spread of the virus.

Contact tracers help, she says, because "if you know that you're a known contact of a COVID-19 case, then you might be much more hesitant to go out until you know for sure that you're not ill.

"I think it sends a really important message about the need to isolate when one is ill."