New strain of "super infectious" COVID-19 was found in Quebec at the end of December. That's when the cases started dropping.

@verretor That's not necessarily unexpected. If it's actually more infectious it'll make covid burn out faster. That might show up as a drop in cases if they were a bit late to identifying it, the people who are getting infected don't get sick enough to get tested, and they respond with an effective effort at protecting those at risk of getting sick.