This weekly blog is perforce unusually short, not because the worst rate of COVID transmission of the entire year has in any way diminished but because the federal and provincial public health agencies which supply the data are essentially missing in action.  Thus three of the four graphs which constitute our weekly composite chart are unchanged from the previous week and their data reflects the state of the pandemic in mid-December. Half a month represents a very long time for governments to leave Canadians without relevant information upon which to base personal and family exposure decisions at the most social time of the year. 

The most relevant of the four charts is the PCR testing results from municipal wastewater since that provides a direct measure of the COVID viral load in the bodies of Ontarians. As of the most recent reading (December 16), that load was the highest measured in 2023 and two-and-a-half times greater the comparable value a year previously. With more Canadians than ever falling sick, so much for the politically-expedient pretention that the pandemic is over! 

The one significant report which was released just before Christmas was Public Health Canada’s review of currently-significant COVID variants for the week of December 17 to 23. That illustrates the accelerating displacement of the XBB family of recombinant Omicron variants with a new set of significantly-mutated BA.2 descendants. For our summary chart, we are now shading them in blues to better distinguish them from XBB lineages. JN.1 is now Canada’s most dominant variant, accounting for 39% of all new cases and having displaced the previously-dominant HV.1. That represents a growth rate for JN.1 of more than 14 times over the most recent six-week period. Given that nearly all Canadians now have some degree of COVID immunity, that means that JN.1 is the most successful COVID variant yet in terms of its inherent ability to evade that immunity. Thankfully so far, what those variants are evading is our fast-reacting “innate” immune system which protects us from new infections. Once we are infected, our “acquired” immune system works to beat back and hopefully eliminate those infections. Prior exposure from some combination of vaccination and illness explains why, for all but immune-compromised people, hospitalization and/or death are significantly-less-common outcomes than earlier in the pandemic.