CALGARY -- The number of COVID-19 cases in Alberta with an unknown source of infection is on the rise.
According to Alberta Health, of the 10,068 cases currently active in the province, officials can’t pinpoint where 75 per cent of them (7,565) were acquired.
“The concern with these increasing numbers, and in particular the number of cases that we don’t know where the source is, makes it quite challenging to keep the numbers at bay,” said Dr. Vanessa Meier-Stephenson, an infectious disease physician and researcher at the University of Calgary's Cumming School of Medicine.
Meier-Stephenson says with so many people contracting the virus through an unknown source, it increases the chances of people becoming infected through day-to-day activities.
“If we don’t know where people are acquiring these new infections, it makes it really challenging to focus these targeted strategies,” she saidn.
For the last two weeks, the other unknown is exactly how many Albertans have actually been tested because of a technical glitch. The province said the reporting system should be fixed this week.
“There was an error in the lab feed between Alberta Precision Labs and Alberta Health that has now been resolved," said Zoe Cooper, communications director for Alberta Health.
"The data is now in the Alberta Health system and we are working to associate it to the correct date."
Cooper said for the week of Nov. 9 to 15, the average daily number of tests was 13,200. With that the province estimates a 6.5 per cent positivity rate.
Meier-Stephenson says the percentage of positive results is an important measure of how well a population is keeping infections under control.
“The [World Health Organization] has suggested if you have less than five per cent of positives that means you’ve got a reasonable handle and you’re testing enough of your population to pick up all of those cases," she said.
She said incomplete data makes it challenging to put forward policies.
Meier-Stephenson says with increasing cases, everyone can take steps to prevent further spread. Albertans need to be mindful of cohort size, avoiding being around large groups, physical distancing and wearing masks.
“We can all do our part to minimize the risk not only for ourselves but everyone around us," she said.
The province says more contract tracers are coming as AHS expects to have 425 positions hired within the next four to six weeks, bringing the total number of staff on the contract tracing team to 1,200.
Alberta Health says the number of unknown cases varies over time as contract tracers work to identify the source.
“In many cases this can be simple, however as people are engaged in more activities the number of potential exposures to COVID increases," said Cooper. "As case investigation progresses sometimes a common source is identified and cases then have a known source."
