Canada's top doctor says a potentially more infectious strain of the virus that causes COVID-19 has not yet been detected in Canada, but federal officials are mobilizing their genome sequencing networks in an effort to catch it.

One particular lineage of the SARS-CoV-2 virus is appearing to dominate infections in the U.K., with an epidemiologist there suggesting mutations on the new strand could be making it 70 per cent more infectious. Experts say more data is needed before they can verify that, however, and they expect current vaccines to still work on the new strand.

Viruses are constantly changing and mutating, says chief public health officer Dr. Theresa Tam, and Canada has been undergoing sequencing on COVID viral samples for months in an effort to track those kinds of alterations.

News of the revamped strand in the U.K., which has already been found in other parts of the world, has made those efforts more important. And given the way COVID spreads, Tam says she wouldn't be surprised to see this new lineage driving infections in several countries.

"It may become one of the more common strains," Tam said in a news conference Tuesday. "We know how this virus transmits in hidden ways, so it's a possibility for sure.

"But by having a bit of lead time and getting set up, we will be able to detect it should it appear in Canada."

Jason Kindrachuk, a virologist at the University of Manitoba, says genome sequencing of viruses is not new, but it's a painstaking process that takes time.

"You actually go through and you basically try to read out what the genetic code (of the virus) is, and you do that basically letter by letter," he said. "It's extremely powerful: it tells us very specifically and very quickly if there have been changes. But it takes time."

Tam says Canada has been "very active" in genome sequencing over the last few days, utilizing scientific networks across the country to look for the specific U.K. lineage, called B.1.1.7.

Provincial databases have been linked up, Tam said, for a broader look at sequencing information, and the Canadian COVID Genomics Network (CanCOGeN), a not-for-profit organization funded by the Canadian government, has also been involved "to look at what more needs to be done."

"They'll give us a pretty good concept of what's going on," she said. "What we can say is, at this point in time we have not detected this mutation. But we will, of course, inform people as this goes along."

Tam said there are 25,000 sequences currently in Canada's data bank, some of which would have been collected from recent travellers.

That doesn't sound like much, considering Canada has had more than 520,000 confirmed cases of COVID-19 since the pandemic began, but Tam said sequencing efforts in the country have been consistent with those of the U.K., which detected the new variant through the same method.

Kindrachuk says it's not feasible to sequence the virus from every positive COVID test, so labs will do a sampling of them to see if any patterns emerge.

"As people across the globe start to pick up on changes, or there are new variants that are showing up, we have the ability then to look within our own pool of samples to see whether or not we are seeing that (too)," he said.

Tam said the priority for sequencing efforts is now on recent travellers from the area where the strain has been most apparent, and Canada banned travel from the U.K. for a 72-hour period starting Monday in an attempt to stop the new lineage from entering our borders.

Samples from pilot projects in Alberta and at McMaster University in Hamilton, Ont. -- which have been gathering data on COVID infection rates among international travellers coming into Canada's major airports -- are also being targeted for sequencing, Tam said.

While much is still unknown about the potential implications of the new COVID strain, Health Canada said recently there's no evidence to suggest the leading vaccine candidates won't still work against it.

Tam says we can "flexibly adjust our public health measures" as new information becomes available, but the safety precautions officials have been preaching for months -- keeping distance, limiting contacts, washing hands -- will still help stop transmission of the B.1.1.7 strain.

"Is there a probability that this could land in Canada? Yes," Tam said. "The only way to stop it from spreading is by doing what we've been harping about like a broken record."

This report by The Canadian Press was first published Dec. 22, 2020.