An intensive care doctor in Toronto is pleading with political leaders to take bold steps now to impose a lockdown, warning that Ontario's health system could face "total collapse" if the spread of COVID-19 is not slowed.

Dr. Michael Warner is medical director of the intensive care unit (ICU) at Michael Garron Hospital and chairs the critical care section of the Ontario Medical Association.

"It's World War Three," Warner said in an interview with CBC News. "This could be an unmitigated disaster. This is the time to overreact. If I'm wrong, that's great, but at least we're prepared. But if I'm not wrong, then we're in major trouble."

The number of new coronavirus cases in Ontario has grown by an average of 21 per cent daily over the past week. That means the total number of cases is doubling every four days, and if that rate of growth were to continue, Ontario's 2,053 ICU beds stand to run out by mid-to-late April .

"We should expect a massive influx of COVID-19 patients into our hospitals, both ill and critically ill," said Warner.

"We have to be prepared for the worst case scenario," he added. "This is the time to overreact to what potentially could happen, not to hope for the best."

Dr. Michael Warner is the medical director of critical care at Michael Garron Hospital and says Canada should have enforced a mandatory lockdown from coast to coast a while ago. 6:25

Warner is calling for "social distancing without exception" and urging political leaders and public health officials to impose stricter measures to slow the spread of the virus.

"If we don't, the impact on the health care system could be total collapse," he said, urging mandatory lockdowns to be put in place immediately.

"If we do it sooner the long term pain will be less," said Warner. "I don't think it's too late to institute those rules, but time is running out."

In Italy, COVID-19 has overwhelmed the health system and has killed 5,000 people. New reports coming from New York, San Francisco and Seattle suggest hospitals have begun to see surges in patients.

"We've learned from the experience in Italy that once it gets out of control the whole health care system is going to be under siege," said Warner. "The patients who get sick with COVID-19 have very, very severe illness, not kind of a flu-light, but very, heavy severe ICU illness that requires sophisticated [medical] techniques."

Cancelling scheduled surgeries, as many Ontario hospitals are now doing , can help free some beds on regular wards but does little to relieve the pressure in the critical care wards, says Warner. Heart attacks, strokes, car crashes, overdoses and major infectious diseases that are not COVID-19 will continue to happen.

Warner takes little solace from the announcements from Ontario Health Minister Christine Elliott that the province has obtained 300 more ventilators and from Premier Doug Ford that auto parts manufacturers are retooling to build more.

"It's nice to hear that 300 new ventilators have been purchased," said Warner

"It's like saying, 'We need 10,000 people to have heart surgery, we're going to make a bunch of operating rooms equipped with the heart-lung machines, but we're not going to have any more heart surgeons.'"

There are about 400 ICU doctors in Ontario and Warner points out that each one cannot work 24 hours a day, seven days a week.

Equipment such as masks, gowns and gloves to protect hospital workers from the COVID-19 virus is in short supply. Warner says some Toronto-area hospitals "will definitely run out of" that material within weeks, based on the current inventory and the rate it's being used.

"What happens if half the ICU doctors get sick or in quarantine?" he asked. "Who's going to take care of the patients? Let alone the nurses who actually do all the heavy lifting."

Pedestrians wear masks in Toronto as residents engage in social distancing during the COVID-19 outbreak. (Evan Mitsui/CBC)

Warner is calling on Critical Care Services Ontario, a Ministry of Health organization, to create rapid education programs — what he describes as "a crash course in how to be an ICU doctor" — for other specialist physicians, such as cardiologists, surgeons, anesthesiologists.

"We need to get ahead of this. We need to think about the next steps, field hospitals, using airports, stadiums as potential places to take care of patients."

Warner says he's infuriated by unclear and inconsistent messaging about social distancing, leading to instances such as in Toronto on Friday where people formed lengthy lines buy a new video game. He believes the spread of the virus will not be slowed unless the average person heeds the right message.

"The safest number to congregate in is one. Not 50, not 10, it's one," said Warner. "Until the government, public health officials and policymakers are consistent with that message then the public will remain confused."

Foresees 'deluge of patients' unless things change

If the rate of growth of new infections is not slowed, Warner predicts "a deluge of patients coming to hospitals in Canada all at the same time. There's no system on earth that can handle that."

He said he is trying to get his message out through as many media interviews as possible this weekend.

"No amount of time or preparation could make us ready for what could be coming in the days or weeks ahead," said Warner. "I'm trying to scream as loud as I can about this before I go to work on Monday, because once I go to work on Monday, I may not come out for four months."