Having reached our seasonal low in new COVID infections, that rate appears to have remained stable for the past several weeks as opposed to last year when it quickly rose to a somewhat higher level. The current low is also only half that of last year, likely due to the much smaller-than-usual number of Canadians returning from US travel.
The above observations are well-supported by this week’s composite chart. The Ontario test positivity rate has plateaued at roughly half of the 2024 low, as have Ontario COVID hospitalizations and ICU bed occupancy rates.
The more independent Canadian COVID-19 Resource Canada COVID hazard index, which is based on excess-mortality calculations, is slightly lower than last week for both Canada and Ontario. Their estimate of one in 141 Ontarians being currently infected and hence infectious has not been updated.
That said, our composite chart shows one potentially very significant development which has only just been reported by the US Centers for Disease Control. Their biweekly report on the respective “market share” of the currently circulating COVID variants shows the meteoric rise of XFC, the latest recombinant variant and one which wasn’t even on their radar two weeks ago. LP.8.1 remains dominant at 70% of all new infections, but has definitely plateaued and can be expected to start receding. XFC is already in second place, thus far at only 9% but with the potential to mushroom over coming weeks.
Recombination is the viral equivalent of sexual reproduction. New virus particles are normally clones of their respective parents, varying only when a rare RNA copying error changes a gene (i.e. a mutation). Recombination occurs when two different strains simultaneously infect the same human or other cell, resulting in all the genes from both strains being reshuffled, with each of the new viral particles ending up with a different combination. That’s evolution on steroids, with a significant risk that one of those new viruses is better equipped to infect humans or other prey and can therefore quickly shoot up to dominance.
XFC is so new that I have yet to find any information about it on the search engines. We’ll just have to wait to see how it unfolds and what if any changes in symptoms can be expected. I expect that there will be some lag before it appears in Canada (it doesn’t help that the Public Health Canada infobase has been down since yesterday).