According to infectious disease experts, COVID-19 is showing some early signs of a new surge in Alberta, meaning the province could soon follow Ontario, Quebec and British Columbia, which are already battling a seventh wave of the pandemic.
The latest provincial data shows that positive rates are rising, effluent indicators are increasing and a highly infected sub-variant is taking hold.
“The positivity rate is probably increasing consistently enough to call it a trend,” said Dr. Linora Saxinger, an infectious disease specialist at the University of Alberta.
And, according to Saxinger, the more infectious BA.5 variant is increasing as a proportion of positive cases.
“At this point, it’s very likely that this is the dominant strain, and it’s probably increasing,” she said.
“That’s always a concern, because in the past when we’ve had a new option that’s more portable, actually replaces whatever was there before, it’s usually been followed by one kind of jump or another.”
A recent update provided to community physicians by Alberta Health Services shows that of positive cases screened between June 21 and 27, an average of 48 percent were lineages other than BA.2 (which can include BA.1, the variant responsible for the fifth wave, BA.4 and BA.5).
The Y-axis indicates the number of SARS-CoV2 RNA particles detected in each sample. The numbers show the first number multiplied by 10 to the power of the small number above. For example, 2.1 x 10¹5 written out in full is 2,100,000,000,000,000 or 2.1 quadrillion detected RNA particles. (Rob Easton/CBC)
It takes several weeks for the provincial lab to perform full genome sequencing, so it’s unclear, based on publicly available data, exactly how many cases are BA.4 and BA.5, but Saxinger said many will be confirmed as BA.5 after testing is complete.
“Unofficial numbers suggest that BA.5 is…certainly over half of [the cases] we see,” she said.
Data released by the Public Health Agency of Canada, which is weeks out of date, showed in the week of June 12 that BA.5 accounted for 20.4 percent of COVID cases nationally, while BA.4 accounted for 7.4 percent.
“Everybody was kind of gearing up for a bigger fall surge. But the whole BA.5 situation opened up the possibility of a bigger summer jump,” Saxinger said.
University of Calgary researchers check monitoring equipment while tracking traces of COVID-19 in Calgary’s wastewater system last year. (Jeff McIntosh/The Canadian Press)
Increases in waste water
There are also signals in the wastewater that Alberta’s transmission rate is increasing.
“In the last week, we’ve seen some increases in a few of the major centers here in Alberta, which would mean that cases are probably going to start to increase,” said Dr. Michael Parkins, an infectious disease specialist at the University of Calgary Cumming School of Medicine and one of the leaders of the provincial wastewater monitoring program.
These increases have been seen in Calgary and Edmonton, as well as bedroom communities such as Banff and Canmore.
Parkins said the program can now track variants and, depending on the community, BA.4 and BA.5 account for 70 to 90 percent of the SARS CoV-2 signals they pick up in wastewater.
“We know about BA.4 [and] BA.5 for many weeks and only in the last three weeks have we seen this replacement really grow,” he said, noting that effluent monitoring was unable to distinguish between the two sub-variants.
“In other waves, when the replacement happens, we start to see an increase in clinical cases. Right now, we expect to start seeing an increase in cases of COVID-19 that are clinically diagnosed.”
The Y-axis indicates the number of SARS-CoV2 RNA particles detected per milliliter of wastewater. This chart should only be interpreted as a measure of progress against itself and should not be used for comparison to other cities or measurement sites. (Rob Easton/CBC)
Parkins will be watching the data closely in the coming days, but like other experts, he suspects a summer spike is coming.
“I think people were hoping we would see a decline consistent with other respiratory viruses. But what we’ve seen with SARS CoV-2 is that it doesn’t seem to follow those trends, and we have waves that fall outside of traditional time periods,” Parkins said.
“So I suspect we’ll see a summer spike. But that doesn’t preclude us from seeing a fall and winter spike as well.”
What’s not clear now, according to Saxinger, is whether the surge will result in many very mild cases or something worse.
Dr. Linora M. Saxinger, an infectious disease specialist at the University of Alberta, near the Mazankowski Alberta Heart Institute. (John Ulan/Ulan Photography)
“There’s an opportunity, because it’s more portable, [BA.5] it can do what the Omicron BA.2 did, which is go around and find all the susceptibles. And then you really see at least some impact in the hospital and the ICU.”
If that happens, Saxinger said Alberta should consider expanding eligibility for fourth vaccine doses earlier than the fall. And, she said, the importance of the third doses should be “convinced now.”
“If you’ve only had two doses, you have less protection right now, and if things start heating up again, there’s no time like the present.”
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