TORONTO -- Some provinces are showing signs that Canada's battle against COVID-19 may be taking a turn for the better, but health officials and experts aren't ready to celebrate.

Canada's Chief Public Health Officer Dr. Theresa Tam said in a press conference on Wednesday that there is reason to be "cautiously optimistic" that the spread of COVID-19 is slowing with cases in the country now doubling every 10 days or so, compared to every three days in late March.

But Tam warned it's too soon to ease physical distancing measures, and doing so would "be like making our way down the mountain in the darkness."

Prime Minister Justin Trudeau warned on Wednesday it would still be several more weeks before the country will be able to consider reopening business and loosening physical distancing measures.

The Public Health Agency of Canada (PHAC) maintains that nationally "the number of illnesses in Canada is continuing to increase and has not yet peaked," according to an updated report released Wednesday.

Despite Canada's curve growing more slowly than other countries', the national curve doesn't provide a full picture of the pandemic -- there are provincial differences.

Ontario, Quebec and B.C., where three-quarters of the Canadian population live, have approximately 87 per cent of the country's confirmed coronavirus cases. Further underscoring the distinctions, B.C. has one of the lowest mortality rates.

Testing approach, available resources, transparency, hospitalizations, intensive care patients and deaths are all factors that can make one province more susceptible to a surge in case numbers than another.

POSITIVE SIGNS IN SOME PROVINCES, CURVE REBOUNDS IN OTHERS

New Brunswick on Tuesday reported no new cases of COVID-19 for the second time in four days, but the province's chief medical officer cautioned the risks to public health remain.

"We are moving in the right direction, but we have not reached our destination," Dr. Jennifer Russell said in a news conference. "We must maintain our resolve. We cannot let up even for a minute."

Newfoundland and Labrador also reported no new cases of COVID-19 on Tuesday, as well as 16 new recoveries. However, officials warn the province's aging population creates particular risks.

Premier Dwight Ball has noted his province has the highest proportion of seniors in the country, and rates of hospitalizations and intensive-care admissions for COVID-19 are higher among those aged 55 and older.

These factors are common throughout Atlantic Canada, where the four provinces rank highest in the country for seniors per capita, making a jump in COVID-19 cases possible.

Manitoba health officials also announced no new cases of COVID-19 with 99 people having recovered, leaving only 142 active cases in the province.

Cynthia Carr, a Winnipeg-based epidemiologist with two decades of experience interpreting and developing protocols for gathering and analyzing health data, said a decrease in cases doesn’t mean Canadians can stop physical distancing measures.

"Those numbers are only going down because we are doing the right thing. Hopefully these measures can decrease over time, but not yet," Carr said in a telephone interview with CTVNews.ca. "It looks like good news, but from an epidemiological perspective, it's not enough data points to say for sure if we are on a downward trend."

Saskatchewan Premier Scott Moe says his plan to reopen the province's economy could come as early as next week after the province reported just three new cases of COVID-19 on Wednesday. Moe said the reopening would be gradual and he would only do so if case numbers remained low.

Saskatchewan has seen seven straight days of single-digit new cases after a peak of 30 infections in late March. There are currently only 95 active cases in the province.

Infectious Disease Specialist Dr. Abdu Sharkawy told CTV's Your Morning on Thursday that it is too soon to loosen restrictions. He said doing so could have a "forest fire" effect.

"We've done our job with the water bombers and we've gotten some luck with some rain, but there are embers that are still smouldering under the surface. If we ignore those embers, it [will be] very easy for a gust of wind to rekindle them and to be back in the same place we started," he said.

Last week, Alberta and B.C. showed signs that public health measures were starting to work in "flattening the curve" and reducing the spread of COVID-19.

Daily case numbers have since remained relatively low for B.C. with 44 confirmed cases and 3 deaths announced on Wednesday, though cases have spiked again in Alberta.

Alberta health officials reported 138 new coronavirus cases on Tuesday -- the province's highest day-to-day increase since the pandemic began -- in addition to another 129 new cases on Wednesday.

According to Carr's studies, only 5.8 per cent of Canada's tests are coming back positive. Because of this, she says it is "always" more important for Canadians to look at the mortality rate and the number of ICU patients than the daily case count to understand the curve.

"Our mortality rate should go down not up over time because we are putting in protective measures for the vulnerable population and we are putting more resources into testing to prevent the spread -- not just confirm that those who are very sick have the infection," she said.

TESTING REMAINS AN ISSUE

There continues to be a lack of widespread standard testing guidelines across the country, with some provinces testing broadly and others testing based on a stricter criteria that includes travel history and symptoms.

Alberta is testing at one of the highest rates in the world at nearly 1,500 per 100,000 people compared to the national average of 910. Ontario has the lowest testing rate of any province, sending roughly 3,500 tests a day to its labs even though they can accommodate up to 13,000 tests.

Colin Furness, who researches epidemiology at the University of Toronto, says provinces need to broaden their testing criteria to get the outbreak under control and not doing so "is a mistake."

"Provinces are starting to converge on the idea that we are planking the curve, but our lack of widespread testing means we have to wait for longer to see what those trends look like because we may be blind to this big part of the iceberg we cannot see," Furness said in a telephone interview with CTVNews.ca. "We don’t know anything about the asymptomatic population because we’re not testing them."

Despite Ottawa-based Spartan Bioscience having received federal approval for production and distribution of a device it claims can produce COVID-19 test results in less than an hour, Furness is concerned about its accuracy.

"Health Canada went ahead and approved it but we haven’t seen data on its accuracy. There's two kind of mistakes a test can make -- it can fail to notice you're sick if you are and it can also say you're sick when you're not," Furness said.

"If it tells you you're sick and you're not, that's a nuisance. But if it fails to tell you you're sick and you are, then that's a public health threat," he added.

While some provinces are seeing their curves being flatten, Furness said their case numbers can easily go back up.

"No new cases is good news because that means there's no new serious cases," he said. "[But] if there’s birthday parties, funerals and sports games going on without notice and spread is happening in the background we could have another spike in a few weeks from now without any idea why or where they come from."

OUTBREAKS IN LONG-TERM CARE HOMES

Dr. Theresa Tam said on Monday said that nearly half of Canada's COVID-19 deaths are nursing and retirement home patients, and even with more safeguards in place, she says more deaths in these settings are likely.

Quebec and Ontario have been hit hardest and continue to see surges in the number of infections due in part to growing outbreaks at long-term care homes.

As of Wednesday morning, Ontario has reported 98 outbreaks at long-term care homes across Ontario, which includes the deaths of 144 residents. In Quebec, more than 150 long-term care facilities have reported COVID-19 outbreaks. Half of Quebec's 435 deaths had occurred in seniors homes as of Tuesday with 90 per cent of all deaths being people over 70.

Carr says ensuring better protections for those living in long-term care homes may "prevent the opportunity for a second wave."

"Our highest risk group is our vulnerable, older population, particularly those in long-term care facilities… We need to turn resources there to focus on what needs to be done for ongoing wellbeing of that population so they are more resilient to these kinds of outbreaks," Carr said.

Despite low daily case numbers, B.C. health officials say a number of community outbreaks are continuing to spread in nursing homes which may increase its count in the coming days.

A total of 265 residents and staff have been infected with the novel coronavirus at 21 living facilities in Metro Vancouver and the Fraser Valley.

Provincial Health Officer Dr. Bonnie Henry said on Wednesday that B.C. would need to consider a number of factors before setting a date for restrictions to be eased, including cases in neighbouring provinces, the ability to monitor outbreaks at the U.S. border and the capacity of B.C.'s healthcare system.

"When we look at data over time, we expect numbers to go up and down, but our ultimate goal in controlling a pandemic is to increase the number of days between cases doubling," Carr said. "The more days we can go without any cases at all, the longer it should be before cases double again."

INDIGENOUS COMMUNITIES MAY IMPACT CURVE

Carr says Canada's northern Indigenous communities are considered "the most vulnerable" if COVID-19 begins to spread because of their remoteness.

"Our Indigenous communities are at highest risk because they have different access to healthcare, they need to leave the community often to get healthcare and there's many people living with chronic conditions," she said.

So far, the territories have kept infections to a minimum with eight confirmed cases in Yukon, five in the Northwest Territories and none in Nunavut.

Prime Minister Justin Trudeau announced on Tuesday that the federal government is spending $130 million to help communities in the North withstand the COVID-19 pandemic.

Carr said it may only be a matter of time before those numbers increase.

"Nunavut has a highly spread out population and because of the cold weather, people tend to stay inside and are less likely to get together because the infrastructure isn't there," Carr said. She added that a combination of lack of healthcare, overcrowded housing and challenges accessing healthy food if Canada's supply chain is disrupted would create spikes in Indigenous case numbers.

CANADA COMPARED TO OTHER COUNTRIES

Several countries have successfully flattened the curve -- most notably China, according to figures from Johns Hopkins University.

When the outbreak began, China saw a peak of more than 14,000 new cases of COVID-19 in one day. Now, China has reported less than 100 new cases and 30 deaths a day since early March.

South Korea's daily reported cases dropped into the double-digits in April, after the country reported more than 800 new cases at its peak on March 29. Although the country did not impose a nationwide lockdown, it did close schools and has not yet reopened them.

Spain, Germany and New Zealand are also showing promising signs that their curves are flattening.

Sharkawy said that Canada can learn something from these countries.

"If a message is taken up very well and if everyone adheres to that message and doesn't resist we can do very well. We saw that in Singapore, in Hong Kong and in South Korea," Sharkawy said. "The population didn't really rebel, they were very adherent [and] very patient with the measures that were proposed by their governments and they've done a fantastic job flattening their curves.

"I think we can do the same thing in Canada if we continue to follow the message of our public health recommendations."

With files from The Canadian Press, visualizations by Jesse Tahirali