EDMONTON -- An Alberta doctor who was one of dozens of healthcare workers to contract COVID-19 at a curling bonspiel in Edmonton last March has co-authored an observational study about the experience.

Dr. Kelly Burak, a professor of medicine at the University of Calgary, says the study published Tuesday shows how infectious the disease is and how transmittable it can be in indoor settings. 

"We had 73 curlers and overall we had an attack rate of 74 per cent, which included confirmed cases by swab and probable cases that tested negative or didn't have access to testing," Burak told CTV News Edmonton. 

In total, 40 of the curlers tested positive for the disease while an additional 16 developed symptoms.

All 73 curlers who participated in the bonspiel – 55 of whom were active healthcare workers – were interviewed for the study.

The standardized interviews took place between April 17 and May 5 of last year.

"We realized that there was something to be learned from the experience," said Burak. "This was a long time ago, but the takeaways are COVID is very infectious." 

Burak points out that at the time of last year's superspreader event there were very few known cases in the community.

"Now we're in a situation where we have the variants, which are more infectious, that are starting to transmit in our community. So it does feel a lot to me like déjà vu."

The U of C professor also notes that some of the confirmed case subjects never developed antibodies, while others lost antibodies.

"That's telling you that it's still important to get the vaccine, if you've had COVID," said Burak.

He says another takeaway from the study is how risky it can be for people to gather indoors while not wearing masks.

"Talking loudly, speaking to other people, sharing food and drink," said Burak. "This is risky behaviour for catching COVID-19 and so I think there is a word of caution as we start to open restaurants and bars right now."

Looking back to that March bonspiel, Burak says in some ways it was fortunate that his group was made up of so many healthcare professionals.

"When I got my first test back and it was negative I was like, 'I don't believe that, that's gotta be a false negative test,' and pushed for repeat testing," he said. "Six out of our confirmed 40 cases were negative on their first swab." 

This year's bonspiel has been cancelled. Burak says the group is looking forward to curling again in Regina in 2023.