The man arrived at Dr. Vatsal Trivedi's intensive care unit in early March with a fairly typical set of risk factors for his age.

He was elderly, or at least close to it, with high blood pressure, diabetes and some lung and heart disease. His oxygen levels were also dangerously low — a hallmark of advanced COVID-19. It marked the first time Trivedi had encountered a suspected case of the often-relentless respiratory illness.

For the downtown Toronto anesthesiologist, the moment was surreal.

He likens it to standing on the shore, knowing a tsunami may be approaching. But somehow, it also felt routine; the product of years of training and practice and a duty to care for the sickest of patients.

So, much like he'd done thousands of times before, Trivedi put on protective gear and began the high-risk intubation procedure, carefully inserting a plastic tube down the man's windpipe so he could be connected to a ventilator, the machine that would move air in and out of his lungs to keep him alive.

The man died a few days later. Trivedi has cared for a steady flow of COVID-19 patients ever since.

Unnerving stories

Now, like many of his colleagues, he's grown acutely aware of the risks borne by front-line workers treating highly contagious patients amid uncertainty over personal protective equipment levels and unnerving stories of hospital staff being infected — and dying — abroad.

"There is nothing unique about us that makes us immune to this infection," Trivedi said. "We are as much at risk as everyone else."

Already, more than 620 Ontario health-care workers have tested positive for the coronavirus that causes COVID-19 — through a variety of transmission sources beyond health-care settings — including one staff member at Brampton Civic Hospital who likely acquired it in his community, and later died after being treated in the hospital's ICU.

At least 15 hospitals also have confirmed outbreaks of the respiratory illness, with 33 cases reported so far among staff according to the latest provincial figures, which don't break down the numbers by individual hospitals.

Ontario public health data compiled by CBC News shows there have been confirmed cases among front-line workers in at least four Toronto hospitals, three Guelph hospitals, three Mississauga hospitals, and at least one hospital in Orangeville and Hamilton.

That's on top of more than 69 reported outbreaks in Ontario long-term care homes, involving more at least 347 infected staff members.

As the number of cases among staff and patients rise, some say health-care workers have growing reason to worry about what's coming next.

"They are scared and frightened and torn — really torn — on their obligations and rights," said Dr. Sandy Buchman, president of the Canadian Medical Association.

A staff member at an Ontario long-term care home wears full personal protective equipment amid an outbreak among the residents. (Evan Mitsui/CBC)

'The hospital is not going to cover my funeral'

One nurse, a casual worker at a Toronto hospital whose identity CBC News is protecting due to her precarious employment, said she recently decided to stop picking up shifts after learning two of her colleagues had tested positive for the coronavirus.

The revelation came while her team was being directed to ration surgical masks, with nurses only being given two per shift, she added. With three young children at home, and a growing sense her own health could be at risk, the nurse said she doesn't plan to return to work until there are adequate supplies of personal protective gear.

"The hospital is not going to cover my funeral," she said. "The hospital is not going to look after my family."

For Buchman, these anxious times call to mind the SARS crisis in 2003. Back then he was working as a family physician, caring for hospitalized patients in Mississauga and watching friends and colleagues fall ill.

That strain of coronavirus ultimately infected fewer than 450 people across the entire country, with health-care workers making up close to half of all the cases, including two nurses and a physician who wound up among the 44 dead.

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Already COVID-19 has proven more widespread and deadly. The number of lab-confirmed cases across Ontario alone is at more than 5,700 and climbing — with health-care workers making up around 11 per cent of those cases.

And the toll on the province's hospitals, and their staff, is growing.

Staffers testing positive

So far, at least 49 staff members at the Trillium Health System in Peel region — including Trillium Health, Credit Valley Hospital and Mississauga Hospital — have acquired COVID-19, according to data compiled by CBC News.

In Guelph, 25 staff at the Guelph General Hospital have tested positive, along with three staff members at Homewood Health Care and three at St. Joseph's Health Centre.

In Toronto, 14 staff members have tested positive at the Centre for Addiction and Mental Health, along with seven at Mackenzie Health's Reactivation Care Centre, three at West Park Healthcare Centre's Functional Enhancement Unit, and three at the University Health Network's Hillcrest Reactivation Centre.

Orangeville's Headwaters Health Care Centre has 16 staff members who've tested positive while St. Joseph's Healthcare Hamilton has six.

In most cases, the transmission source was either unclear or not provided.

With a surge of patients still expected, Buchman believes health-care workers will ultimately bear a "disproportionate burden" even worse than during the SARS outbreak.

"We were dealing with an epidemic of a severely contagious and fatal disease," he said. "But nowhere the magnitude and rapidity that COVID-19 is descending upon us."

'Duty to serve'

Joel Lockwood, an emergency physician at a downtown Toronto hospital, agreed there's a level of anxiety among health-care workers, both thanks to the memories of SARS and the catastrophic impact of COVID-19 on the health-care systems of Italy, Spain, and cities south of the border.

"We have a duty to serve," Lockwood added, "but I don't think that's unlimited."

The trauma team leader does take solace in his hospital's "culture of safety," however.

While he acknowledged fears of personal protective equipment shortages and limited testing supplies are in the back of many colleagues' minds, Lockwood said it's counteracted at hospitals like his by heightened cleaning procedures, strict patient screening and innovation when it comes to using protective gear.

The federal government is exploring how to disinfect and reuse protective masks, for instance, while all levels of government across the country have been working to procure millions of new supplies.

Still, Trivedi said the situation remains unpredictable. While physicians like him know what they signed up for — and spent years training for — he said it's still unsettling hearing reports of potential equipment shortages.

Then there are the stories from Trivedi's friends working in the U.S. who already lack proper protective gear, and now face daily decisions over whether to put themselves at risk of acquiring a potentially deadly disease while caring for someone who could die without their help.

"When it comes down to your own health, it's a decision I hope I don't have to make," Trivedi said.

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Lauren Pelley can be reached at lauren.pelley@cbc.ca