Experts say no firm answer yet on why Saskatoon has hundreds more active COVID-19 cases than Regina

Saskatchewan's two largest cities are dealing with significantly different COVID-19 situations. Experts say there isn't yet a firm explanation why.

There were 966 known active cases in Saskatoon and 162 in Regina as of Tuesday, according to the province's dashboard.

Joseph Blondeau, head of clinical microbiology at Royal University Hospital and the University of Saskatchewan, said there are theories as to why there's such a big difference, but no concrete answers that he's aware of.

Blondeau said Saskatoon could be seeing more cases because the city has the largest population in the province and therefore is more susceptible to outbreaks.

He also said people from around the province travel to Saskatoon for a variety of reasons, which could lead to more cases.

"It may simply be a population issue as opposed to anything else, and I don't have a better answer than that because I don't know that we have a better answer than that," he told CBC Radio's Blue Sky.

Jason Kindrachuk, assistant professor and Canada research chair of emerging viruses at the University of Manitoba, said he has some theories, but couldn't offer a definitive explanation — especially since vaccination rates are similar in each city.

As Tuesday, 70 per cent of people in Saskatoon who are eligible for a vaccine were fully vaccinated, according to the  provincial Ministry of Health, while 73 per cent of eligible people in Regina had been full vaccinated.

One of Kindrachuk's theories is that there may be some underlying immunity from the wave Regina saw in March and April, during which Regina reported its highest active case count of 1,121 on April 5.

"We know that certainly people with prior infection will have some amount of immunity back toward this virus, so that certainly could play into it," he said.

Another possibility, he said, is that the delta variant is present in different demographics in each city.

"Age groups that are infected now tend to be skewing younger, but we also know that certainly in populations with lower socioeconomic status, those that are minorities, those that are living in congregate settings, all those things can lead to acceleration of transmission."

Kindrachuk said more explanations should become available as epidemiologists dig into the rise in cases.

In the meantime, he said provincewide precautions should be implemented, even if some regions are seeing lower numbers than others.

"Even though [cases] may not be taking off now, that doesn't necessarily mean the trajectory isn't going to change and start to go on an upswing," he said.

He said not having provincewide restrictions makes the virus more difficult to control, as there aren't consistent precautions in place to prevent it from spreading from one region to another.

He also said the health-care system will continue to be pushed to the brink as long as more cases continue to appear, regardless of what region they're in.

"ICU capacity is certainly being stretched, health care is being stretched. Saskatchewan, to me, is certainly in a predicament."

As of Tuesday, 154 people were hospitalized with the virus, including 29 in intensive care.

"We've got to get back to working together as communities. We don't have a choice," he said. "As more people are spending time indoors, this is really the period where we have to try to get this under control."