[Goose]

Contract tracing has been happening in  NY, FL, TX, CA, and all the other state.

Undoubtedly. But to what extent? 1) What percentage of the cases are traced? 2)What percentage of the cases supply contacts? 3)What percentage of the contacts are reached? It seems pretty clear to me that the news must be horribly bad, because nobody wants to talk about it and declare success. San Francisco supplies 1 and 3 of the above, but without 2 you have no idea what 3 means. SCC has a difficult to interpret "Cases by Source of Transmission". The percentage listed as "Contacts to a case" has been plummeting every since it was added to the site. SMC has nothing. So while one can say they are doing contact tracking and tracing, it isn't effective enough to count.

If any one of them said, we're seeing a lot of cases that we can associate with  X (for any X) then we'd expect X to be in the CA list of things to rein in, or the ones in Texas, or elsewhere.



I don't know why we haven't seen any studies on transmission spots (that I'm aware of).  The little we see, like demographics, are coming out of the government institutions.   Even something as little as saying that N% of the cases are spread in the household would help.  Even SCC's info about construction workers was muddied because no one reported that spread was happening at construction sites, only that there were a number of cases being found where they were checking symptoms before work at construction sites.

Could it be because there results are so spotty that they are meaningless?

I was looking at San Antonio numbers.  Of the 21K cases, they have identified sources for 7800 of them.  Of those, 57% are close contact, 37% are community spread, 6% travel.   I wonder if that is distorted by the easy cases of "I know I got it from a household member".   If so, that suggests that maybe only about 20% (4440/21000) are from easy-to-identify contacts.

I would interpret the numbers as follows: of the 21k cases, we only contacted 7800 of them. We won't say how many we actually tried to contact and failed and how many we didn't even try. Of those 7800 cases, we figured out 57% of them (probably). 37% we either got no cooperation or didn't find an "obvious" source. 6% could be travel, but no actual way of knowing.

Most importantly, of those 21k cases, how many of them were in quarantine as previously named contacts? They don't say. That latter number reveals what effect contact tracking and tracing has on R0. If it is a very small number, contact tracking and tracing is accomplishing little. Granted, with this virus lots of "contacts" may quarantine, never feel sick, and not ever test positive. But at least 60% (current worst case Fauci number) will get sick enough to count. Adjust accordingly.

If one quits wondering why they aren't doing contact tracing and starts wondering why contact tracing isn't identifying the sources (even if only for the infectees), one begins to think that community spread is easier and perhaps more unreliable than we've been thinking.   But it is really hard to follow the embers in a wild fire.

Especially if you ignore 2/3rds of them. It is also possible there aren't enough people available to search for trends in the data that is being collected. If one is a conspiracy theorist, it could also be because there is/could be an obvious trend but the Counties don't want to take the steps that are necessary to "fix" the problem. Therefore, they don't make the results available.

[Goose]

Contract tracing has been happening in  NY, FL, TX, CA, and all the other state.

Undoubtedly. But to what extent? 1) What percentage of the cases are traced? 2)What percentage of the cases supply contacts? 3)What percentage of the contacts are reached? It seems pretty clear to me that the news must be horribly bad, because nobody wants to talk about it and declare success. San Francisco supplies 1 and 3 of the above, but without 2 you have no idea what 3 means. SCC has a difficult to interpret "Cases by Source of Transmission". The percentage listed as "Contacts to a case" has been plummeting every since it was added to the site. SMC has nothing. So while one can say they are doing contact tracking and tracing, it isn't effective enough to count.

If any one of them said, we're seeing a lot of cases that we can associate with  X (for any X) then we'd expect X to be in the CA list of things to rein in, or the ones in Texas, or elsewhere.



I don't know why we haven't seen any studies on transmission spots (that I'm aware of).  The little we see, like demographics, are coming out of the government institutions.   Even something as little as saying that N% of the cases are spread in the household would help.  Even SCC's info about construction workers was muddied because no one reported that spread was happening at construction sites, only that there were a number of cases being found where they were checking symptoms before work at construction sites.

Could it be because there results are so spotty that they are meaningless?

I was looking at San Antonio numbers.  Of the 21K cases, they have identified sources for 7800 of them.  Of those, 57% are close contact, 37% are community spread, 6% travel.   I wonder if that is distorted by the easy cases of "I know I got it from a household member".   If so, that suggests that maybe only about 20% (4440/21000) are from easy-to-identify contacts.

I would interpret the numbers as follows: of the 21k cases, we only contacted 7800 of them. We won't say how many we actually tried to contact and failed and how many we didn't even try. Of those 7800 cases, we figured out 57% of them (probably). 37% we either got no cooperation or didn't find an "obvious" source. 6% could be travel, but no actual way of knowing.

Most importantly, of those 21k cases, how many of them were in quarantine as previously named contacts? They don't say. That latter number reveals what effect contact tracking and tracing has on R0. If it is a very small number, contact tracking and tracing is accomplishing little. Granted, with this virus lots of "contacts" may quarantine, never feel sick, and not ever test positive. But at least 60% (current worst case Fauci number) will get sick enough to count. Adjust accordingly.

If one quits wondering why they aren't doing contact tracing and starts wondering why contact tracing isn't identifying the sources (even if only for the infectees), one begins to think that community spread is easier and perhaps more unreliable than we've been thinking.   But it is really hard to follow the embers in a wild fire.

Especially if you ignore 2/3rds of them. It is also possible there aren't enough people available to search for trends in the data that is being collected. If one is a conspiracy theorist, it could also be because there is/could be an obvious trend but the Counties don't want to take the steps that are necessary to "fix" the problem. Therefore, they don't make the results available.