A tale of two festivals

[mindstalk]

Lollapalooza sees little outbreak.

Sturgis rally followed by surge of cases

Cook Country, IL

Meade County, SD.

Granted Meade is much smaller population than Cook. But comparing South Dakota to Illinois, or even just Cook, isn't much better.

Comments

[elusiveat]

The Lollapalooza results really startle me for an unmasked event. I didn't think the vaccine was terribly effective at stopping the new variants, just at preventing hospitalizations, but this seems like notable evidence that they really do work.

I wonder what other behavioral differences among participants in the two events might be relevant. The Sturgis rally article says "While much of the rally is outdoors, another study was conducted on how the rally affected caseloads in neighboring Minnesota showed that the primary infections that could be traced appeared to occur indoors, in a restaurant setting." That seems potentially important, but I can't imagine that the Lollapalooza participants weren't going to restaurants as well.

Hmm, I guess another thing that we need to take into account is that the people attending Lollapalooza might have been more likely to self-quarantine beforehand. Hum.

[mindstalk]

If vaccines are (made-up but plausible number) 66% instead of 95% at stopping infection, that both allows for lots of alarming breakthrough cases but also really slows things down. Everything I've seen is that they do reduce chance of infection, as well as the length of infection period, they're just not as silver bullet as we hoped.

Lolla people were supposedly 90% vaccinated. I would guess masking in downtown Chicago is higher than in South Dakota.

Holland had an outbreak but vaccination was a pass right away, no waiting period. https://www.cnbc.com/2021/07/15/music-festival-in-holland-leads-to-over-1000-covid-infections.html

UK had "more than 1000 cases" but a line implies 432 *entered* infectious. https://www.bbc.com/news/uk-england-suffolk-58323500

Another contrast article, also noting low vaccination in SD https://www.thedailybeast.com/sturgis-rally-is-what-a-vaccine-era-coronavirus-superspreader-event-looks-like

[elusiveat]

Yeah, I feel like the baseline model is that the difference comes down to vaccination rates.

It occurs to me that my thinking might be a bit muddied by the fact that I'm interested in who actually has the virus, whether or not they are symptomatic, but that asymptomatic vaccinated people might not be likely to bother getting tested. The public health question then becomes whether there is a meaningful danger of infected but asymptomatic people bringing the virus home to unvaccinated children and sparking a surge among children. That might delay detection for a cycle, but my overall impression is that we have at least some evidence that that isn't a major concern.

Overall, I think this is pretty good evidence that the vaccine is decently effective at stopping spread, but there are enough other variables in play that I would like to know more about the bigger picture before drawing a final conclusion.

One answer might be that 60-70% effectiveness---which seems about right (again, these are kind of made up numbers) for both the effectiveness of the vaccines at completely stopping the Delta variant, and also the effectiveness of masking at stopping person-to-person infection---might be enough of a change to the dynamics of this virus that it stops spreading so readily. That kind of effectiveness *feels* low to me, but masking seems startlingly effective, even when I almost never see people wearing their masks correctly.

[mindstalk]

Naively, if vaccines reduce transmission by 2/3, and masking by 2/3, vaccine + masking turns R=8 into R=8/9, less than 1.

Substitute 'outdoors' for 'masking' for most of Lolla.

[elusiveat]

I have a hard time believing that being outdoors provides equivalent protection to masking if everyone is packed in close, especially if they're in a context where they'll be yelling and cheering.

But this virus keeps defying my intuitions at every turn, so really, at this stage I feel like I don't know anything.