Canada’s first known case of the coronavirus variant first detected in Brazil has been reported in Toronto.

Toronto Public Health (TPH) confirmed the case in a news release issued on Sunday afternoon. TPH said a resident who travelled from Brazil tested positive for the P.1 variant and is now in hospital.

The local public health unit also reported the city's first case of the South African variant, known as B.1.351, in a Toronto resident with no recent travel history and no known contact with anyone who is a returned traveller.

TPH is investigating a total of 27 confirmed variant of concern cases as of Saturday.

"Scientists and medical professionals are concerned that these variants are more transmissible than the original coronavirus," TPH said in a statement.

"The U.S. Centers for Disease Control and Prevent (CDC) has indicated that research is ongoing to determine more about these variants to better understand how easily they might be transmitted and the effectiveness of currently authorized vaccines against them."

There are now two cases of the South African variant confirmed in the province. Last week, health officials reported that the variant was detected in a man in Mississauga. Officials said the case had no known connection to travel and that it was likely acquired in the community.

Additionally, there are 174 cases of the B.1.1.7 variant, which was first detected in the United Kingdom, in the province. Ontario modellers had said that the B.1.1.7 variant will become the dominant strain in the province by March.

According to a report from Public Health Ontario released last week, more than five percent of Ontario's COVID-19 cases on Jan. 20 were from variants of concern.

Of the 1,880 positive samples from that day that were analyzed, 103, or 5.5 per cent, were confirmed or highly likely to be either the UK B.1.1.7 or South African B.1.353 variants of concern.

Public Health Ontario ramped up capacity to screen all positive COVID-19 tests for known variants last week as part of the Ontario government's six-part plan to tackle the emergence of variants. Mandatory testing for all international travellers arriving at Pearson airport also began last week.

Speaking to CP24 Sunday evening, infectious diseases specialist Dr. Isaac Bogoch said the new cases of the South African and Brazil variants are concerning.

"Both of those variants of concern really raise a red flag, and the reason being is that the vaccines don't have the same degree of efficacy against those variants as they would, for example, against something like the variant discovered in the United Kingdom," said Bogoch, who is also part of the province's vaccine distribution task force.

While there are still many unanswered questions about the Brazil variant, he said that its mutations are "somewhat analogous" to B.1.351. This is worrying, Bogoch noted, because some studies have found that some vaccines may be less effective against the South African variant.

On Sunday, South Africa halted its Oxford/AstraZeneca vaccine rollout after early trial data found that it appeared to offer only limited protection against mild disease caused by B.1.351. The Oxford/AstraZeneca vaccine has not been approved for use in Canada.

"It's important to note that those vaccines, based on the data that we have available, they still prevent severe illness, they still prevent death, but they don't have the same level of protection that they would against non-variant strains of COVID-19," Bogoch said.

"We don't have all the answers. It's extremely important to proceed with caution."

Despite the threat posed by COVID-19 variants, the province will reportedly announce this week the gradual reopening of the economy in some areas while extending the stay-at-home order in other regions.

Bogoch hopes officials take a cautious approach in reopening Ontario because he said these variants are the "real deal."

"We know what these variants of concern can do. I know sometimes you might hear people, for lack of a better word, sweep it under the rug and maybe tone down how important they are," he said. "They are important."

The doctor said a third wave is preventable as long as cases continue to head in the right direction and better vaccine coverage is put in place.

"We have to have plans in place that even if there is a slow and careful reopening that we're not going to see a rise in cases," Bogoch said.

"There's no reason to have a third wave at all, so let's do the right thing. Let's keep those case numbers going down."

- with files from Chris Herhalt, The Canadian Press, The Associated Press, Reuters