The latest provincial data shows that positivity rates are rising, sewage indicators are rising and a highly contagious sub-variable is taking over. “The positivity rate is probably trending up enough to call it a trend,” said Dr. Lynora Saxinger, an infectious disease expert at the University of Alberta. And, according to Saxinger, the more virulent variant BA.5 is increasing as a percentage of positive cases. “At this point, it’s very likely the dominant strain, and it’s probably growing,” he said. “That’s always a concern because in the past, when we’ve had a new variant that’s more contagious, it basically replaces what was there before, it’s usually followed by one kind of increase or another.” A recent update provided to community physicians by Alberta Health Services showed that, of the positive cases tested between June 21 and 27, an average of 48 percent were lineages other than BA.2 (which can to 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 in full is 2,100,000,000,000,000 or 2.1 quadrillion RNA particles detected. (Rob Easton/CBC) It takes several weeks at the provincial lab to conduct 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 of them will be confirmed as BA. 5 once the test is complete. “Unofficial numbers suggest that BA.5 is… definitely more than half [the cases] we see,” he said. Data released by the Public Health Agency of Canada, which has not been updated for weeks, shows in the week of June 12 that BA.5 accounted for 20.4 per cent of COVID cases nationally, while BA.4 7.4 percent. “Everyone was preparing for more of a fall surge. But the whole BA.5 situation opened up the possibility of more of a summer surge,” Saxinger said. University of Calgary researchers check monitoring equipment as they monitor traces of COVID-19 in the sewer system in Calgary last year. (Jeff McIntosh/The Canadian Press)
Sewage lifts
There are also signals in the wastewater that Alberta transmission rates are increasing. “We’ve seen in the last week some increases in a lot of the big centers here in Alberta, which would mean 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 surveillance program. These increases have been seen in Calgary and Edmonton as well as bedroom communities such as Banff and Canmore. Parkins said the program is now able to 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 receive in wastewater. “We knew about BA.4 [and] BA.5 for many weeks, and just in the last three weeks we’ve seen that replacement go up,” he said, noting that wastewater surveillance is unable to differentiate between the two subvariants. “In other waves, when the replacement happens is when we start to see the increase in clinical cases. So right now, we expect to start seeing an increase in clinically diagnosed cases of COVID-19.” The Y-axis indicates the number of SARS-CoV2 RNA particles detected per milliliter of wastewater. This graph should only be interpreted as a measure of progress against itself and is not used for comparison with other cities or measurement locations. (Rob Easton/CBC) Parkins will be watching the data carefully in the coming days, but like other experts he suspects a summer wave 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 don’t go beyond traditional time periods.” , Parkins said. “So I suspect we’ll see a summer spike. But that doesn’t preclude us from also seeing a fall and winter spike.” What’s unclear now, according to Saxinger, is whether the surge will lead to many very mild cases or something worse. Dr. Lynora M. Saxinger, an infectious disease specialist at the University of Alberta, near the Mazankowski Alberta Heart Institute. (John Ulan/Ulan Photography) “There’s a possibility that because it’s more contagious, [BA.5] it can do what the Omicron BA.2 did, which is to browse and find all sensitive people. And then you really see at least some impact in the hospital and the ICU.” If that happens, Saxinger said Alberta would have to consider expanding eligibility for fourth vaccine doses earlier than the fall. And, he said, the importance of third installments needs to be “hammered home 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.”
