Omicron subvariant BA.2 reported in Canada: PHAC

The Public Health Agency of Canada (PHAC) says it has detected more than 50 cases of a new Omicron subvariant known as BA.2.

In an emailed statement to CTVNews.ca on Wednesday, PHAC confirmed that 51 cases of the BA.2 subvariant have been reported in Canada, mainly from international travellers.

BA.2 is a descendant of the highly transmissible Omicron variant and has been found in at least 40 countries as of Wednesday, according to global coronavirus data sharing platform GISAID.

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PHAC said it is monitoring BA.2, as it does with all new COVID-19 variants, and maintains that Canadians should continue to follow the advice of public health officials.

"While the impact of all variants continues to be monitored in Canada, the Government of Canada knows that vaccination, in combination with public health and individual measures, is key to reduce the spread of COVID-19 and its variants," PHAC said.

BA.2 was first detected in November 2021 and the U.K. designated it a "variant under investigation" on Friday, saying it could have a growth advantage.

While the World Health Organization (WHO) has not yet dubbed BA.2 a "variant of concern," it is tracking the sub-lineage's spread.

The Omicron variant, B.1.1.529, has four sub-lineages: BA.1, BA.1.1, BA.2 and BA.3.

The BA.2 sub-lineage is widely considered "stealthier" than the original version of Omicron because some of its genetic traits make it harder to detect. Some scientists say it could also be more contagious, however, they acknowledge there are still a lot of unknowns about the subvariant.

• What's known about 'stealth' version of Omicron?

PHAC said BA.2 has "many similarities" to BA.1, but does exhibit some differences, including in mutations that may affect transmissibility, detection and possibly immune escape.

"There is very limited evidence at present to determine how impactful the differences between BA.1 and BA.2 may be, hence the ongoing efforts by PHAC scientists to monitor cases here in Canada and track developments internationally," PHAC said in the statement.

Infectious disease expert Dr. Isaac Bogoch said "significant degree of uncertainty" remains around BA.2, but the subvariant is worth keeping an eye on as more cases are reported around the world.

"We have a lot of BA.1 for example here in Canada, we also have BA.2. What's interesting is, in other jurisdictions, we're seeing growth of BA.2 whereas BA.1 might be on the downslope," Bogoch told CTV News Channel on Wednesday. "Again, something to keep an eye on for now."

Despite this, Bogoch said Canadians should not be concerned. He noted that the effectiveness of COVID-19 vaccines against BA.2 will likely be "very similar" to the BA.1 sub-lineage.

"It's not the same [as BA.1], it's probably a little bit more transmissible, but there's probably a lot of other similarities," Bogoch said.

"I think it's too soon to know exactly how this manifests and we need to learn more," he added.

With files from the Associated Press