07-21-2020, 07:19 AM
Clearly there is some set of dynamics that is allowing the spread of the disease. In SCC, the graph of cases by collection date continues to grow. Last full week of data was higher every weekday than they highest of the week before.
It doesn't look like we can point to LTCF as the cause of the high numbers. That seems to be under control this week.
However, I've never seen a fire truck bring wood to a fire. Opening more avenues for spread seems illogical. It was unfortunate, in my opinion, that SCC opened things up on July 13 amid ever increasing cases.
SCC has added another page of data. Among the tables there is Cases by Method of Transmission. Of the 7795 cases, only 5145 are classified (updated 7/20):
362 7.0% Outbreak associated (LTCFs?)
1050 20.5% Contact to a Case
37 0.7% Travel
3696 71.7% Unknown/Presumed Community Spread
[We should check a week from now to find out if these numbers go up by a week's worth of cases. Then see the ratio of Contact to Unknown in the delta.]
I continue to be surprised at how few "Contact to a Case" there are. I hear about spread in households, Wikipedia states that average household household size is just under 3 in SCC, so if the disease hits everyone in the household of someone who got the disease by community spread, I'd expect AT LEAST 67% Contact to a Case.
Remember that "Contact to a Case" is an upper bound on the effectiveness of contact tracing. I see nothing to suggest that these cases were detected by contact tracing before the individual already knew they had the disease.
So, I'm heartened to think that, with all the pre-symptomatic exposure one would get in a household, maybe it isn't hitting entire households. Indeed, at 20%, it sounds like it is rarely spreading to even a second person in a household.
On the other hand, that means that whatever contact tracing we have is failing miserably (not necessarily to lack of effort, but perhaps by the nature of the disease) to identify the next round of cases. Even if contact tracing is too late, you'd expect that if Adam spread it to Bill, and then Bill got the call from contact tracing after he already knew he was sick, Bill's case would be a "Contact to a Case".
So, I would suggest that means our definition of what is a "close contact" is inadequate. Maybe you don't need 15 minutes of contact, maybe any contact (walking down an empty aisle in a grocery store) is sufficient.
I would also suggest that maybe the presumption of spread by droplet/aerosol may be unwarranted. Maybe it is putting your hands on the grocery cart or door handle that is how you are getting it. (Of course, getting it on your hands isn't enough, you then have to move it to your mouth, eyes, nose.)
In my mind, I continue to wonder about spread through the frozen food supply (not necessarily what you eat, but the packaging). That could cause regional differences in spread (CT has different frozen food supply chain than CA). But I expect health departments are well versed in detecting food supply spread of diseases. (I don't REALLY believe this is behind hot spots, but I can't rule it out. This isn't likely to cause the every increasing case numbers.)
Is anyone aware of any studies measuring whether SARS-COV-2 is detectable on community surfaces or frozen food, or in the air in busy spaces in the hot spots (perhaps versus non-hot spots)? The only studies I've seen are in hospitals or doctor's offices. Does anyone know what evidence the CDC uses to claim that spread is mainly via droplets? Their page on COVID spread uses "is thought to spread mainly ...". That doesn't sound like they have much evidence. Knowing that it does spread by droplets to close contacts is not sufficient to say it mainly spreads that way.
It doesn't look like we can point to LTCF as the cause of the high numbers. That seems to be under control this week.
However, I've never seen a fire truck bring wood to a fire. Opening more avenues for spread seems illogical. It was unfortunate, in my opinion, that SCC opened things up on July 13 amid ever increasing cases.
SCC has added another page of data. Among the tables there is Cases by Method of Transmission. Of the 7795 cases, only 5145 are classified (updated 7/20):
362 7.0% Outbreak associated (LTCFs?)
1050 20.5% Contact to a Case
37 0.7% Travel
3696 71.7% Unknown/Presumed Community Spread
[We should check a week from now to find out if these numbers go up by a week's worth of cases. Then see the ratio of Contact to Unknown in the delta.]
I continue to be surprised at how few "Contact to a Case" there are. I hear about spread in households, Wikipedia states that average household household size is just under 3 in SCC, so if the disease hits everyone in the household of someone who got the disease by community spread, I'd expect AT LEAST 67% Contact to a Case.
Remember that "Contact to a Case" is an upper bound on the effectiveness of contact tracing. I see nothing to suggest that these cases were detected by contact tracing before the individual already knew they had the disease.
So, I'm heartened to think that, with all the pre-symptomatic exposure one would get in a household, maybe it isn't hitting entire households. Indeed, at 20%, it sounds like it is rarely spreading to even a second person in a household.
On the other hand, that means that whatever contact tracing we have is failing miserably (not necessarily to lack of effort, but perhaps by the nature of the disease) to identify the next round of cases. Even if contact tracing is too late, you'd expect that if Adam spread it to Bill, and then Bill got the call from contact tracing after he already knew he was sick, Bill's case would be a "Contact to a Case".
So, I would suggest that means our definition of what is a "close contact" is inadequate. Maybe you don't need 15 minutes of contact, maybe any contact (walking down an empty aisle in a grocery store) is sufficient.
I would also suggest that maybe the presumption of spread by droplet/aerosol may be unwarranted. Maybe it is putting your hands on the grocery cart or door handle that is how you are getting it. (Of course, getting it on your hands isn't enough, you then have to move it to your mouth, eyes, nose.)
In my mind, I continue to wonder about spread through the frozen food supply (not necessarily what you eat, but the packaging). That could cause regional differences in spread (CT has different frozen food supply chain than CA). But I expect health departments are well versed in detecting food supply spread of diseases. (I don't REALLY believe this is behind hot spots, but I can't rule it out. This isn't likely to cause the every increasing case numbers.)
Is anyone aware of any studies measuring whether SARS-COV-2 is detectable on community surfaces or frozen food, or in the air in busy spaces in the hot spots (perhaps versus non-hot spots)? The only studies I've seen are in hospitals or doctor's offices. Does anyone know what evidence the CDC uses to claim that spread is mainly via droplets? Their page on COVID spread uses "is thought to spread mainly ...". That doesn't sound like they have much evidence. Knowing that it does spread by droplets to close contacts is not sufficient to say it mainly spreads that way.