Alberta could be on verge of seventh pandemic wave, experts warn

COVID-19 is showing some early signs of another upswing in Alberta, according to infectious disease experts, meaning the province could soon follow the likes of Ontario, Quebec and B.C., which are already battling a seventh pandemic wave.

The latest provincial data shows positivity rates are rising, wastewater indicators are increasing and a highly contagious subvariant is taking over.

"The per cent positivity has been probably trending up consistently enough to call it a trend," said Dr. Lynora Saxinger, an infectious disease specialist with the University of Alberta.

And, according to Saxinger, the more infectious BA.5 variant is growing as a proportion of positive cases.

"At this point, it is very likely to be the dominant strain and likely increasing," she said.

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"That's always a concern because in the past when we've had a new variant that's more transmissible basically replace whatever was present before, it's usually followed by one or another kind of a surge."

A recent update provided to community physicians by Alberta Health Services indicated that, of the positive cases screened between June 21 and 27, an average of 48 per cent were lineages other than BA.2 (which can include BA.1, the variant responsible for the fifth wave, BA.4 and BA.5).

It takes the provincial lab several weeks to conduct full genome sequencing, so it is 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 testing is complete.

"The unofficial numbers would suggest that BA.5 is … for sure over half of [the cases] we're seeing," she said.

Data published by the Public Health Agency of Canada, which is weeks out of date, shows during the week of June 12 that BA.5 accounted for 20.4 per cent of COVID cases nationally, while BA.4 accounted for 7.4 per cent.

"Everyone was kind of gearing up for more of a fall surge. But the whole BA.5 situation has opened up the possibility of more of a summer surge," Saxinger said.

Wastewater upticks

There are also signals in wastewater that Alberta's transmission rates are rising.

"We have seen in the last week some upticks in several of the major centres here in Alberta, which would signify that cases will likely start to be on the rise," said Dr. Michael Parkins, an infectious disease specialist with the University of Calgary's Cumming School of Medicine and one of the leaders of the provincial wastewater surveillance program.

Those upticks have been observed 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 per cent of the SARS CoV-2 signals they're picking up in wastewater.

"We've known about BA.4 [and] BA.5 for many weeks, and it's only in the last three weeks that we've seen this replacement just really shoot up," he said, noting the wastewater surveillance isn't able to differentiate between the two subvariants.

"In other waves, when the replacement occurs is when we start to see the uptick in clinical cases. So right now is when we expect to start to see an increase in the COVID-19 cases that are clinically diagnosed."

Parkins will be watching the data closely in the coming days, but like other experts he suspects a summer surge is coming.

"I think people had hoped we would see a fall surge consistent with other respiratory viruses. But what we've seen with SARS CoV-2 is it doesn't seem to follow those trends, and we have waves that fall outside traditional time periods," Parkins said.

"So I do suspect we're going to see a summer surge. But that doesn't preclude us from seeing a fall and winter surge as well."

What is unclear now, according to Saxinger, is whether the wave will lead to a lot of very mild cases or something worse.

"There is a possibility that because it's more transmissible, [BA.5] might do what Omicron BA.2 did, which is go around and find all the susceptible people. And then you do actually see at least some impact in hospital and 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 third doses needs to be "hammered home now."

"If you've only have two doses, you do have less protection right now, and if things are starting to heat up again, there's no time like the present."