Open this photo in gallery Lloyd Lartey sprays disinfectant during a visual demo of the enhanced cleaning being used on TTC bus touch points at the Wilson Yard in North York, Ont., on Toronto on March 3, 2020. Tijana Martin/The Globe and Mail

Ontario’s policy for protecting health-care workers against COVID-19 wastes precious resources and leaves hospitals unable to safely cope with an expected rise in coronavirus patients in the coming days, infectious disease experts warn.

Ontario’s Health Ministry is advising health-care workers to use what are known as “airborne precautions” when treating patients with suspected or confirmed cases of COVID-19, the name of the disease caused by the new coronavirus.

Airborne precautions include the use of negative pressure rooms, which are specially designed isolation rooms with ventilation systems that prevent air from escaping. Airborne precautions also include the use of N95 respirator masks to help block small airborne particles.

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But numerous infectious disease experts say mounting evidence shows COVID-19 spreads through droplets, such as when an infected person sneezes and coughs, and that airborne precautions are not appropriate nor are they supported by evidence. Instead, they say health professionals should use “droplet precautions,” which refer to gowns, eye guards, gloves and regular surgical masks.

“I don’t know where the ministry gets its advice,” said Michael Gardam, infection-control expert and chief of staff at Toronto’s Humber River Hospital.

Dr. Gardam and other infectious disease experts are calling for the province to change its policy as the number of COVID-19 cases in Ontario and British Columbia rises. On Tuesday, Ontario announced two new cases of the disease and B.C. said it had four more, bringing the national total to 33. All confirmed cases have been linked to international travel, but experts say it’s only a matter of time before local person-to-person transmission starts here.

The new cases announced in B.C. bring the province’s total to 12, with seven of those cases linked to Iran. Provincial Health Officer Bonnie Henry said that Nowruz, the Persian New Year, is approaching and said that while large gatherings are still considered safe, anyone returning from either Iran or China is asked to self-isolate for 14 days.

Prime Minister Justin Trudeau said Tuesday that he is confident Canadian health officials are taking the right approach and that the federal government will do what it can to minimize the impact of the outbreak.

Ontario is the only province recommending airborne precautions. B.C. uses droplet precautions and none of the COVID-19 cases there have spread to health-care workers. Other countries, including Germany and Australia, are also using droplet precautions.

Dr. Gardam said the decision to use airborne precautions could make it more difficult for health-care workers to respond to the expected rise in cases, particularly given the scarcity of negative pressure rooms.

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“The challenge down the road, if we do start seeing community spread, we’re going to overwhelm our hospital resources in terms of negative pressure rooms almost immediately,” said Dr. Gardam, an infection-control expert who was on the front lines during the 2003 outbreak of severe acute respiratory syndrome (SARS).

He said the continued use of airborne precautions could also dissuade health professionals from testing more individuals for COVID-19 because as soon as individuals are suspected of having the virus, they must be placed in a negative pressure room, which is hard to come by.

“That’s going to be a huge impediment to testing people,” Dr. Gardam said. “If we have to continue to care for these patients in negative pressure rooms, there won’t be enough."

Dr. Gardam said Ontario should follow the Public Health Agency of Canada’s advice and use droplet precautions and reserve the airborne rules for higher-risk procedures. For instance, clinicians may have to perform a bronchoscopy on a COVID-19 patient, which involves inserting a scope into the patient’s lungs. Such procedures require health-care professionals to be close to a patient’s airway and also causes individuals to cough much more, heightening infection risk.

There is also a looming shortage of N95 masks, which means health-care workers should conserve them for higher-risk situations, said Janine McCready, an infectious diseases physician at Michael Garron Hospital in Toronto.

“We would never want to be in a situation where we wouldn’t have adequate protection for people later on if an epidemic does arrive here," she said.

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Allison McGeer, director of the infectious diseases epidemiology research unit at Mount Sinai Hospital’s Lunenfeld-Tanenbaum Research Institute in Toronto, said the policy must be changed to ensure supplies are available.

“We don’t want to be making the mistake of using all our respirator [masks] for things we don’t actually need them for,” Dr. McGeer said.

In an e-mail statement, Ontario’s Health Ministry said it implemented airborne precautions in December as news of the virus emerged and that as evidence surrounding COVID-19 improves, officials will “evaluate and update our guidance as appropriate.”

With reports from Kristy Kirkup and Andrea Woo

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