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This past week has seen a continued acceleration in the month-long trend of rising levels of new but relatively mild COVID infections. As illustrated in our composite chart, municipal wastewater viral counts (the timeliest indicator of pandemic trends) climbed more steeply than anytime since last spring. We had already seen the sharp rise in PCR test positivity rates (a key statistic which Ontario publishes only every second week). COVID hospitalizations have now followed suit, showing a significant rise both in Ontario and nationally. Predictably, Canadian COVID deaths have also risen modestly for the first time in several months.
Turning to the viral mix, the bi-weekly US CDC variants report highlights the continuing diversification of the utterly dominant XBB family. EG.5 (an XBB.1.9.2 derivative) has the highest “market” share with only 22% of new cases. It is slowing down in the sense of having less than doubled its share over the past eight weeks, and will likely be challenged for dominance by one of its own progenies, HV.1, which surged by a factor of more than ten (to 5%) over that same period. BA.2.86, the new, unusually-highly-mutated non-XBB variant, which has been in the news recently and which we discussed last week, has yet to appear in either the CDC top-30 or the shorter Public Health Canada list. If it fails to emerge within the next couple of weeks, we could safely assume that it is insufficiently transmissible to compete with the currently dominant XBB strains and will disappear.
It is now clear that the intrinsic seasonality which brought a five-month respite in COVID infection rates is now ending. The resumption of classes can only accelerate viral spread and waning “herd immunity” among those whose most recent infection or vaccination was more than six months ago virtually guarantees continued worsening in the weeks and months ahead. It is worth noting that even in Kingston, which has traditionally been among Canada’s best-vaccinated communities, less than 8% of those eligible have bothered to get their free booster in the past six months.