Omicron variant lurks in Manitoba samples

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This article was published 25/02/2022 (1511 days ago), so information in it may no longer be current.

There are now four confirmed cases of a more contagious Omicron variant in Manitoba, the province has confirmed.

The first case of BA.2 (a sub-type of Omicron) was detected in the province Feb. 10, and three others were confirmed this week, a provincial spokesperson said Friday.

The variant is believed to be more contagious than the original Omicron strain, but it’s not yet known whether it causes more severe illness.

The Cadham Provincial Laboratory sequences about 10 per cent of positive COVID-19 PCR test results from across the province. Sequencing of certain test results is also done at the request of public health officials, the spokesperson stated in response to questions about the level of genetic sequencing Manitoba is doing to detect emerging variants.

Only PCR test results are included in the sampling, but most people only have access to rapid-antigen tests, which aren’t counted in Manitoba’s results.

“Introduction or establishment of any new strain would be detected using this sampling method. To date, Omicron BA.1 is by far the most dominant and established strain, brief introductions of Delta or BA.2 have been noted recently but do not seem to be establishing themselves,” the province stated.

At the federal level, Canada relies on a border-surveillance program to check for emerging strains of COVID-19. Canada tests all unvaccinated travellers and a random selection of travellers arriving from the U.S.

A random, representative sample of those positive test results are then sequenced at the National Microbiology Lab in Winnipeg to look for variants.

“The proportion sequenced varies with testing volumes, current border stance, and total sequencing capacity, and is adjusted to ensure sufficient sensitivity to detect low prevalence new variants,” a spokesperson from the Public Health Agency of Canada stated.

In a Friday morning briefing, Canada’s top doctor said the presence of BA.2 is increasing in Canada, now showing up in about 10 per cent of the country’s domestic COVID-19 samples.

Dr. Theresa Tam said the original strain of Omicron (BA.1) is still the dominant COVID-19 variant in most provinces. In Denmark, where BA.2 is now dominant, it hasn’t been shown to cause more severe illness, but Tam said the unvaccinated are still at highest risk.

“Knowing that the vaccines are still expected to provide substantial protection against serious illness really underscores the message that people need to get their COVID-19 vaccines up to date,” she said.

— with files from Dylan Robertson

katie.may@winnipegfreepress.com