[Snorlax94]

...
It feels to me that there is more going on here than just ambient UV.

Considering that 54% of SCC cases are from unknown contacts, maybe fomites are playing a bigger role than the CDC currently acknowledges.

I know of a case last week in a food service that has me concerned about how many secondary infections could be from fomites from this one person.  I believe that if you went to a eating establishment (indoors, outdoors, to-go), and a server, cashier, or cook got sick, or you go ot a grocery store where a cashier or stocker got sick, you wouldn't be informed.  If you got sick, you'd be in that 54% with unknown contacts.

The 54% of SCC cases from unknown contacts and "community spread" are so concerning and maddeningly frustrating. So many of us were looking to contact tracing to get a handle on this thing. The cup half-full view is that maybe it takes a full cycle to get contact tracing down and we'll be prepared next time.

As for the speculation regarding fomites, I keep thinking back to that Korean call center study.

I think it was a 15 story building where they tested 1,145 contacts. The first case was on the 10th floor, but from then on, 97% of the confirmed cases were all on the 11th floor, and of those, almost all of them were in close range.

If fomites were such a formidable source of spread, I'd expect more of the infections to break out beyond the 11th floor, and to pass to co-workers on different floors and on the opposite side of the building.

And although I could be over-reliant on this one study, from a different country that may have very different practices (how often do employees go to break rooms, etc.), the contact tracing in the US has been so weak and inconclusive that I'd still probably trust studies like the S Korean one more. They had a contained system -- one building, and they jumped on it with a ton of investigators and testing. This leads me to believe we frequently have no idea where it came from not because the spread is from mystery fomites, but because our contact tracing is failing to uncover the contacts. Some day we'll know, but my guess right now is that many people are lying. By "always wears a mask", I suspect they mean except for the weekends when they go to 1-2 indoor house parties that they don't want to tell the contact tracers about. I believe there are *some* mystery cases of people who truly always wear masks and never mingle unnecessarily, but my guess is that the true rate is very, very low. Another possibility is that a fair chunk of of the mystery community spread is coming in the eyes. My impression is that a lot more people in Korea and China wear glasses, so maybe that is why their contact tracing and containment is so much more successful.

[Snorlax94]

...
It feels to me that there is more going on here than just ambient UV.

Considering that 54% of SCC cases are from unknown contacts, maybe fomites are playing a bigger role than the CDC currently acknowledges.

I know of a case last week in a food service that has me concerned about how many secondary infections could be from fomites from this one person.  I believe that if you went to a eating establishment (indoors, outdoors, to-go), and a server, cashier, or cook got sick, or you go ot a grocery store where a cashier or stocker got sick, you wouldn't be informed.  If you got sick, you'd be in that 54% with unknown contacts.

The 54% of SCC cases from unknown contacts and "community spread" are so concerning and maddeningly frustrating. So many of us were looking to contact tracing to get a handle on this thing. The cup half-full view is that maybe it takes a full cycle to get contact tracing down and we'll be prepared next time.

As for the speculation regarding fomites, I keep thinking back to that Korean call center study.

I think it was a 15 story building where they tested 1,145 contacts. The first case was on the 10th floor, but from then on, 97% of the confirmed cases were all on the 11th floor, and of those, almost all of them were in close range.

If fomites were such a formidable source of spread, I'd expect more of the infections to break out beyond the 11th floor, and to pass to co-workers on different floors and on the opposite side of the building.

And although I could be over-reliant on this one study, from a different country that may have very different practices (how often do employees go to break rooms, etc.), the contact tracing in the US has been so weak and inconclusive that I'd still probably trust studies like the S Korean one more. They had a contained system -- one building, and they jumped on it with a ton of investigators and testing. This leads me to believe we frequently have no idea where it came from not because the spread is from mystery fomites, but because our contact tracing is failing to uncover the contacts. Some day we'll know, but my guess right now is that many people are lying. By "always wears a mask", I suspect they mean except for the weekends when they go to 1-2 indoor house parties that they don't want to tell the contact tracers about. I believe there are *some* mystery cases of people who truly always wear masks and never mingle unnecessarily, but my guess is that the true rate is very, very low. Another possibility is that a fair chunk of of the mystery community spread is coming in the eyes. My impression is that a lot more people in Korea and China wear glasses, so maybe that is why their contact tracing and containment is so much more successful.