One week after Alberta lifted virtually all COVID-19 restrictions, many people are keeping a close eye on the more infectious delta variant — while still low in numbers, it continues to smoulder in the province.

Alberta identified 21 more variant cases, including 10 of the delta strain, in its daily update on Wednesday.

And the Calgary zone has had the most cases by far, recording 694 of the 831 B.1.617 cases to date in the province.

Dr. Stephanie Smith, a University of Alberta hospital infectious disease specialist, said there are a lot of encouraging signs in the province — including the dramatic drop in overall COVID-19 cases and decreased pressure on hospitals.

"But I think we're not quite out of the woods yet," said Smith.

Sixty per cent of Alberta's active COVID-19 cases are variants of concern and many of those are the delta strain.

"The proportion is climbing with respect to delta," she said. "Roughly half of the variant cases now are the delta variant."

Smith said delta is on track to become the dominant strain and she's worried about large gatherings, including the Calgary Stampede, which has announced a number of COVID-19 precautions.

"Is there the potential to have some sort of super spreader event in those situations given that we still do have some delta in the community? I think the answer is yes."

Just over 43 per cent of Albertans are fully immunized, leaving large swaths of the population unprotected.

Until a higher proportion of eligible Albertans have two doses of the COVID-19 vaccine, there is still a risk for clusters, particularly in Calgary, where 84 per cent of the delta cases have been concentrated, Smith said.

Throwing 'gasoline on that fire'

At the University of British Columbia, zoology professor and mathematical modelling expert Sally Otto has been tracking the delta variant. 

She said Alberta's plummeting case numbers are driven mostly by a drop in the old wild-type of coronavirus and the older variants of concern (alpha and gamma).

"Those are all coming down and declining pretty steeply," she said.

Delta, though, is a different story.

"The delta numbers are low, but they aren't declining."

Otto said Alberta's reopening on July 1 gave the more transmissible variant a window.