Source: Calculated from NY Times Github COVID data repository, data reported through 2/5/2021.
Cases are now down 50% from the peak. The faster rate of decline that appeared to start circa 2/1/2021 continues.
New York leads the way in faster rate of decline. Not sure if that’s significant or not.
It’s still too soon to attribute that accelerating decline to the the combination of increasing herd immunity (infections + vaccination) plus existing COVID hygiene (masking, etc.). That’s still my best guess, and that’s what I termed the “emission level of herd immunity” in earlier posts. Not “70% must be vaccinated”, but more like “40% immune by any means, plus all your COVID hygiene measures on top”.
The best explanation of the decline in new cases continues to be “seasonality”, i.e., no explanation at all. Sometime before Christmas, the rate of new infections began to fall, and that showed up about two weeks later in the reported data. And that has continued to decline. And now, appears to be declining at a faster rate.
But the cross-section of states isn’t validating that “remission herd immunity” explanation for that. Yet. Maybe. At least, not my naive interpretation of what I’m seeing. Only a handful of states appear to be showing a visibly more rapid decline in new cases/ 100,000/ day.
Interesting, one of the states that is showing a visibly faster decline in new COVID cases per day is New York (circled in the charts below). I had a reader comment that lack of testing early on would have meant a higher higher ratio of total cases to diagnosed cases for the first wave of the pandemic. And so, using one number to inflate reported cases to total cases would (e.g.) understate total cases in states hard-hit in the first wave. While I understand that this is likely, I didn’t think the magnitude would be enough to matter. That said, the ratio of deaths to cases in those first-wave states was vastly higher than was the case later in the pandemic.
Is it possible that I’m grossly underestimating true post-infection cases in the first-wave states (NY, NJ, maybe CA)? And I should therefore expect to see the sharper downturn there, first, rather than the Midwest? Maybe, but it’s too late to change my story now. I’ve got my marker down for “remission herd immunity”. And I pinned that to seeing the downturn sharpen in the Midwest, because that was the area with the highest count of diagnosed cases. In that situation, it’s no fair changing your mind after-the-fact, once you’ve peeked at the data.
Separately, there’s something odd going on with the deaths data. That’s for the next post.
The state charts with data as of 2/5/2021 follow.