Open this photo in gallery A patient is brought into the emergency unit of the Verdun Hospital, Thursday April 2, 2020 in Montreal. The Globe and Mail asked several hospitals for the number of workers sick with the disease but they either declined to provide the information or did not respond by deadline. Ryan Remiorz/The Canadian Press

Four hospitals in Ontario have declared an outbreak of the coronavirus after dozens of workers tested positive for COVID-19, just as the province braces for the full force of the pandemic.

The hospitals are all part of Wellington-Dufferin-Guelph Public Health, northwest of Toronto. The disease has cut a wide swath in the region, endangering everyone from physicians and nurses to dietitians and maintenance workers, said Dr. Nicola Mercer, Medical Officer of Health for the region. Guelph General Hospital has been hardest hit, with 21 cases of COVID-19 as of Thursday. The outbreak began in the hospital a week ago, when four workers on the same ward tested positive.

In all, 33 hospital workers in the region have tested positive for the disease, demonstrating how easy it is to transmit COVID-19 once it infiltrates a facility.

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“This virus is very infectious,” Dr. Mercer said in an interview. “It is easily transmitted person to person, and the social-distancing measures are often difficult to do in a health-care environment.”

COVID-19 in Ontario, by public health unit As of April 2, noon (ET) CASES: 2,204 Durham Peel Ottawa Fewer than 50 50 to 100 100 to 200 200 to 300 More than 300 None DEATHS: 53 York Toronto 1 to 2 2 to 4 4 to 6 6 to 8 8 to 10 None MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: GOVERNMENT OF ONTARIO COVID-19 in Ontario, by public health unit As of April 2, noon (ET) CASES: 2,204 Durham Peel Ottawa Fewer than 50 50 to 100 100 to 200 200 to 300 More than 300 None DEATHS: 53 York Toronto 1 to 2 2 to 4 4 to 6 6 to 8 8 to 10 None MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: GOVERNMENT OF ONTARIO COVID-19 in Ontario, by public health unit As of April 2, noon (ET) CASES: 2,204 Durham Peel Ottawa Fewer than 50 50 to 100 100 to 200 200 to 300 More than 300 None DEATHS: 53 York Toronto 1 to 2 2 to 4 4 to 6 6 to 8 8 to 10 None MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: GOVERNMENT OF ONTARIO

The toll the coronavirus has taken so far in one of Ontario’s 34 public-health units offers a glimpse of what might be in store for front-line health-care workers elsewhere. The Ontario government does not release statistics on the number of COVID-19 cases for each health unit.

A spokeswoman for Health Minister Christine Elliott said a total of 274 health-care workers in various institutions, including hospitals and long-term-care homes, had tested positive as of Thursday. While this represents one in 10 cases in the province, the spokeswoman said, it does not necessarily mean the workers all got the disease on the job. They could have taken ill by coming in close contact with someone else with the disease.

Ms. Elliott told reporters on Thursday that the government has put a human-resources strategy in place to provide replacements while hospital workers are away, self-isolating at home for 14 days.

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“We know they’re doing really, really difficult work right now," Ms. Elliott said. "And we want them to stay both mentally and physically healthy.”

Hospitals in Ontario run the gamut from prestigious teaching institutions to community ones in smaller cities and towns. Few have been spared from the coronavirus, based on a random sample of hospitals pro-actively disclosing the number of patients who have tested positive for COVID-19.

Hospitals under the University Health Network umbrella in Toronto, the largest in Canada, had 18 in-patients, including nine in intensive care, as of Thursday. Michael Garron Hospital in the city’s east end had eight and Windsor Regional Hospital had 15, up from 10 the previous day.

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In all, 405 patients with COVID-19 are currently in hospital in Ontario, said Dr. Barbara Yaffe, the province’s Associate Chief Medical Officer of Health. Of those, 167 are in intensive care.

The Globe and Mail asked several hospitals for the number of workers sick with the disease but they either declined to provide the information or did not respond by deadline.

In the Wellington-Dufferin-Guelph region, Dr. Mercer said the majority of COVID-19 cases are with staff rather than patients. Guelph General Hospital has two patients with the disease, compared with the 21 workers. Headwaters Health Care Centre in Orangeville has nine workers and one patient, and Homewood Health Centre in Guelph, one of the province’s largest mental-health and addictions hospitals, has two workers. St. Joseph’s Health Centre in Guelph, a complex-care hospital, has one infected worker.

“What this means is the health-care providers are not giving it to the patients,” Dr. Mercer said.

Like everywhere else in Ontario, hospitals in Dr. Mercer’s region are struggling with a shortage of crucial protective equipment, including face masks, to keep workers and patients safe. The shortage comes just as hospitals prepare for a significant increase in the number of patients expected over the next two weeks, she said.

Doctors and nurses in the region are coping with the shortage of face masks by sterilizing and reusing them instead of discarding the protective coverings after one wearing, as is normally done. “The shortages are so significant that we are having to reuse some pieces of equipment in a safe manner,” she said.

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With a report from Laura Stone

Prime Minister Justin Trudeau says he will soon be able to give Canadians a better sense of the impact COVID-19 is going to have on this country but he isn’t able to do it yet. The Canadian Press

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