The official COVID-related statistics released this past week are predictably indicative of a moderate rise in new COVID infections as we slide back into the respiratory virus season. The difference this year is that the rise started early and from roughly double to 2023 low point for new infections.
As discussed in this blog last week, the critical Ontario wastewater testing numbers are no longer a reliable indicator because, thanks to a typical Doug Ford move, they are now based solely on four non-representative Toronto sewage processing sites. I have therefore switched to the Canada-wide graph, which is also less reliable because most of the Ontario data is missing. Our most up-to-date predictive indicator is the PCR test positivity rate for the minority of Ontarians still eligible for testing, which clearly shows the rising infection rate. Hospitalizations are rising more modestly but, again, at nearly double the number from last year at this time. COVID ICU occupancy is so far more stable.
The more independent estimate by COVID-19 Resources Canada statisticians of the number of Ontarian currently infected and therefore infectious was not updated this week. Its last estimate was one in 74.
The most recent Public Heath Canada analysis of currently-circulating COVID variants shows the KP.3.1.1 strain having achieved dominance, accounting for 51% of all new infections. That represents a more than 4-fold increase over the past six weeks. It is but the most recent of its KP-prefixed family, which together amount to 85% of new cases. At this point in the pandemic, the most prevalent strains are almost definitely those genetically most adept at evading existing human immunity to infection. That immunity also wanes over time, being much less effective by six months after one’s most recent booster shot and/or infection. The currently available booster shot was formulated against last year’s XBB strains. A new version, formulated against KP.3’s KP.2 cousin strain, has been approved by the US CDC but not yet in Canada. While I’m now eligible for my next shot, I plan to hold off until September or October in the hope of getting the new one.