The first person who tested positive for a variant of COVID-19 in the Kingston, Ont., area caught it in a different community that's grappling with over 100 likely cases of the more infections strain, officials said, warning that further examples of such spread will be seen if residents aren't careful.

The medical officer of health for the Kingston, Frontenac and Lennox and Addington health unit said the infected person had travelled to the Simcoe-Muskoka area and is believed to have been infected there.

Dr. Kieran Moore noted that the case is not believed to be connected to a large outbreak involving variant cases at a long-term care home Barrie, Ont., that has infected well over 200 people.

Instead, the Kingston-area resident is believed to have been infected with the more transmissible U.K. variant of COVID-19 in the broader Simcoe-Muskoka community, he said.

“It was just someone that had traveled for business purposes, who was exposed, and then brought it back,” he told reporters Tuesday. “That's what's going happen if we're not careful on a regular basis.”

Moore said that case has been linked to four other cases in his region, but all those people have since recovered and spread of the variant seems to have been limited to that group.

His public health unit has now recommended that anyone returning from travel outside the region, or who has visitors from outside the region, get tested for COVID-19.

In Toronto, where 14 cases of the U.K. variant had been detected as of Wednesday, the city's medical officer of health said the new strains have marked an “uncertain” stage of the pandemic, one year after the first positive case was confirmed in the country.

“Medically, we are in an uncertain phase of the pandemic,” Dr. Eileen de Villa said. “The emergence of coronavirus variants is one feature of this uncertainty.”

She said restricting travel between regions is “worth considering,” but it will depend on what's discovered in ongoing studies.

Of three new strains labelled “variants of concern,” only the U.K. variant has been found in Ontario.

Public Health Ontario officials said this week that current science suggests the U.K. variant is more infectious and potentially causes more severe illness. It has been tied to an increasingly dire wave of infections across Europe, prompting some governments to introduce harsh new measures.

Ontario is working to increase capacity to screen for the new variants -- a process that takes several days -- and as of Wednesday, 51 cases had been confirmed in the province, though local health officials in various regions have said they suspect the number is higher.

Premier Doug Ford called this week for further restrictions at entry points to Canada to keep new strains of the virus out.

Epidemiologist Dr. Nazeem Muhajarine, a professor at the University of Saskatchewan, said in an interview that restricting travel is a good first line of defence against such new mutations -- but the window may passed for Ford's proposal to help against the U.K. variant in particular.

“I think it's a little bit too late, because the variant has already made it in,” he said Wednesday.

However, Muhajarine said border controls such as requiring isolation after travel can also be used effectively to control spread between different provinces and regions within them.

He pointed to the success seen in Atlantic Canadian provinces that imposed stricter isolation rules on travellers early in the pandemic, and have since kept infections comparatively low.

He said early patterns emerging in Barrie and elsewhere in Ontario with the U.K. strain are “concerning,” as people are once again dealing with a potentially more dangerous virus that's still being studied.

Testing enough samples to find the new variants should be the “first order of business,” Muhajarine said, and control measures can buy time while building up capacity for such testing.

Communication to the public will also be key, he said, and in the meantime, people should be cautious and follow many of the same precautions -- wearing masks, distancing and staying home when possible.

“You wouldn't do anything really different than what you've been doing all along to keep yourself safe,” he said. “If anything, you sort of assume that it has suddenly gotten a little bit more threatening and dangerous out there and act accordingly.”

- with files from Denise Paglinawan.

This report by The Canadian Press was first published Jan. 27, 2021.