That's a pretty far cry from "the winter wave started at Sturgis."
> Following a 10-day motorcycle rally in South Dakota attended by approximately 460,000 persons, 51 confirmed primary event-associated cases, 21 secondary cases, and five tertiary cases were identified in Minnesota residents.
That's a drop in the bucket compared to the community spread in the US in 2020.
I'm not saying Sturgis was a great idea, but I am saying that the winter wave would have happened regardless.
I was going to make a similar comment, after having drawn the association above.
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.
That study wasn't about finding all the cases that originated from the rally. That was just proving that in fact, people who never attended the rally got sick with the same genomic-markers as the COVID19 present at the rally.
Which means that the "spread" of COVID19 from Sturgis -> Minnesota cannot be denied.
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.
I've read through the study pretty carefully, and it does appear to have tried to be comprehensive. Specifically:
All confirmed cases among Minnesota residents were reported to MDH. MDH or local public health department staff members interviewed patients with confirmed SARS-CoV-2 infection to identify exposures and persons who might have been in contact with patients during their infectious period (2 days before through 10 days after symptom onset).* To assess exposures, interviews included questions about travel and being in specific settings, such as bars or restaurants, schools, health care facilities, or events or social gatherings in the 14 days before symptom onset. During August–September 2020, MDH and local health department staff members interviewed >80% of patients with a confirmed SARS-CoV-2 infection.
If the survey missed cases, it wasn't for lack of trying. That's not to say it didn't miss some.
(Keep in mind I'm the person who'd suggested the relationship above.)
> Following a 10-day motorcycle rally in South Dakota attended by approximately 460,000 persons, 51 confirmed primary event-associated cases, 21 secondary cases, and five tertiary cases were identified in Minnesota residents.
That's a drop in the bucket compared to the community spread in the US in 2020.
I'm not saying Sturgis was a great idea, but I am saying that the winter wave would have happened regardless.