What the study does show is that the Sturgis variant was epidemiologically detectable throughout Minnesota following the rally. Note that the total number of samples was drawn from identified interviewed patients only, though this appears to have covered all reported cases in MN during the period (August 1 -- August 31, 2021). My understanding is that the survey was as comprehensive as could be achieved, and not a limited sampling.

During the same period, the 7-day average new-daily-case rate in Minnesota was 699--795 (rising slightly over the course of the month, observed from Worldometers). The Sturgis-linked cases were 0.4% or less of total confirmed cases.

(I'm assuming the CDC tracing was comprehensive, the paper is less than clear on this, though that appears to be the case.)

We could make numerous arguments that the study was flawed, missed cases, was incomplete, etc. All of that would be an argumment from ignorance. And though I feel there's some case to be made for suggesting the CDC undercounted, that leaves us with a weak basis for any further conclusions. Sometimes, though, in epidemiology, that's the best that can be done, and the precautionary principle kicks in: what course of action would provide the maximum benefit and least harm.

Minnesota's Winter Wave really started spiking in October of 2020. It peaked on 20 November at 7,023 NDC (7-day average). Whether or not those cases are linked to Sturgis would require sequencing of a sample and drawing inferences.

That said ...

... other evidence comes from looking at the spread of Covid-19 hot-spots throughout the US from August -- January of 2020--2021. And that did show the radiating pattern I described. I'm not certain it's associated with Sturgis, but it very much walks like a duck.

Which means that the "spread" of COVID19 from Sturgis -> Minnesota cannot be denied.

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http://ftp.iza.org/dp13670.pdf

Page 60 (Appendix 5) shows a nice graph showing the "trendline" of COVID19 cases ("synthetic Meade county"), vs Actual Meade county.

We can see that COVID19 cases spiked pretty hard after the Sturgis rally. Now maybe there was some "other" superspreading event happening in that area at the same time... but Occam's Razor points to the giant 400,000+ person motorcycle rally without any mask precautions going on.

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> That's a drop in the bucket compared to the community spread in the US in 2020.

But you're right on this front. I think the poster earlier is overstating Sturgis's importance. Sturgis is just one event, there were plenty of others with far bigger spread (February 2020 Marti Gras New Orleans, especially because no one took any precautions during that event. It was "before COVID19" was well recognized by the public)

But without a doubt, Sturgis was a superspreading event. But there were _many_ superspreading events happening all over the place, so I personally don't want to put too much importance on Sturgis alone. The fact remains that many other events continued to take place, as that region didn't want to take precautions against COVID19 in general.

That said:

- There's a clear risk.

- Taking measures against the risk would be highly advisable.

- Monitoring the aftereffects, over several months at least, is going to be necessary to draw conclusions.

I'd also like to see a compilation of Covid (or other epidemics) and the interrelationship with other widespread disasters or disturbances. The situation in Afghanistan would be one such case, where there's a sudden breakdown of what limited order did previously exist. Wildfire evacuations in the Pacific Northwest of the US & Canada would be another. There's the long slow emergency of homelessness in California (about 100,000 individuals on any given day, not sure how many are long-term or not).