[Goose]

The problem with the above analysis is timing. The SCC number of positives who were contacts to a case includes all contacts who tested positive at any time. They may have been tested initially and been negative, and then a week/a day later felt ill and got tested. The idea that testing people who are known to have been exposed should result in more positives is reasonable. However, it may be that if you test "immediately", they aren't sick yet. Unless you have THAT number, you don't know how effective immediate testing is. It may be that almost nobody who is asymptomatic tests positive when tested "immediately". Perhaps it is better to wait a few days. I don't know the answer, but unfortunately the "contacts to a case" number doesn't tell us.

No, if I were exposed to COVID on April 1 and tested positive on May 30, then the contact would not have been reported.

Agreed, because you would be beyond the 14 day (at that time the norm) quarantine period. However, if you tested positive on April 5, you would be counted as a contact, as you state below

If the average time to symptoms is 5 days, and a person is infectious 2 days ahead, I'm pretty sure the PCR-RT tests would pick up such an average person around 3 days after exposure.

That is a reasonable plausibility argument. However, many things with this virus that seemed reasonable didn't happen as planned. SCC and all other jurisdictions should know by now what the PDF of the delay from exposure to testing positive. Knowing this, they should be able to chose a "good" time to test. It may be that if you are asymptomatic, there isn't a "good" time because 1) you may have been lucky and didn't get the disease,  or 2) people that remain asymptomatic may generate less viral load and what they do generate may be delayed. These is one known case where the guy tested positive on day 21.

My point is, and remains, that knowing the PDF of conversion to positive should allow testing at an "optimal" time, where optimal is defined in a stated manner, i.e. what the objective is and what the constraints are. Saying that you must test immediately is just as silly as saying you should only test optionally unless you can say why that is so and back it up with numbers. By now, we should have the numbers, say what they are. In both cases, the CDC changed policy without giving us the data justifying the change.

A relative who had an exposure on a specific day (and was quarantined by the next day) was told her county wouldn't test her for 5 days after exposure (remember, in quarantine, you can't go get yourself tested; they have to come to you), and in fact didn't test her for 11 days.  Her 14-day quarantine expired before she knew if she was positive (asymptomatic) or negative.
IMO, she should have been tested at 5 days and at 14 days after exposure (if the first was negative and no symptoms have developed).

Yes, but that is 2 tests, which may increase the delay for other people's test results. It also may not, but again, SCC and all the other jurisdictions should know the sensitivity of delay vs number of tests. The optimal way to test twice, or four times, is undoubtedly different that the optimal way to test once.

More testing (say at 8 & 11 days) can give you a better idea of when the disease starts (if asymptomatic) so you can wait out your 10 days in isolation once you get a positive test.  If you test at 14 days and get a (first) positive, you will need to isolate until 24 days after exposure.  That's a long time when maybe you would have tested positive at day 6.

If she tested negative at 5 days and positive at 14 days, she should be counted as one that got it from a contact.  (Remember, she was in quarantine so she wasn't further exposed.)

I am assuming the SCC contacts to a case number includes anybody who tested positive within 14 days of their known exposures. Not sure that is true, but I think it is. Also, FWIW you can be further exposed in quarantine but not in isolation. In quarantine, you can be quarantined with other people. If one of them converts to positive, the quarantine starts over. It may be your relative quarantined alone, which would amount to isolation.

[Goose]

The problem with the above analysis is timing. The SCC number of positives who were contacts to a case includes all contacts who tested positive at any time. They may have been tested initially and been negative, and then a week/a day later felt ill and got tested. The idea that testing people who are known to have been exposed should result in more positives is reasonable. However, it may be that if you test "immediately", they aren't sick yet. Unless you have THAT number, you don't know how effective immediate testing is. It may be that almost nobody who is asymptomatic tests positive when tested "immediately". Perhaps it is better to wait a few days. I don't know the answer, but unfortunately the "contacts to a case" number doesn't tell us.

No, if I were exposed to COVID on April 1 and tested positive on May 30, then the contact would not have been reported.

Agreed, because you would be beyond the 14 day (at that time the norm) quarantine period. However, if you tested positive on April 5, you would be counted as a contact, as you state below

If the average time to symptoms is 5 days, and a person is infectious 2 days ahead, I'm pretty sure the PCR-RT tests would pick up such an average person around 3 days after exposure.

That is a reasonable plausibility argument. However, many things with this virus that seemed reasonable didn't happen as planned. SCC and all other jurisdictions should know by now what the PDF of the delay from exposure to testing positive. Knowing this, they should be able to chose a "good" time to test. It may be that if you are asymptomatic, there isn't a "good" time because 1) you may have been lucky and didn't get the disease,  or 2) people that remain asymptomatic may generate less viral load and what they do generate may be delayed. These is one known case where the guy tested positive on day 21.

My point is, and remains, that knowing the PDF of conversion to positive should allow testing at an "optimal" time, where optimal is defined in a stated manner, i.e. what the objective is and what the constraints are. Saying that you must test immediately is just as silly as saying you should only test optionally unless you can say why that is so and back it up with numbers. By now, we should have the numbers, say what they are. In both cases, the CDC changed policy without giving us the data justifying the change.

A relative who had an exposure on a specific day (and was quarantined by the next day) was told her county wouldn't test her for 5 days after exposure (remember, in quarantine, you can't go get yourself tested; they have to come to you), and in fact didn't test her for 11 days.  Her 14-day quarantine expired before she knew if she was positive (asymptomatic) or negative.
IMO, she should have been tested at 5 days and at 14 days after exposure (if the first was negative and no symptoms have developed).

Yes, but that is 2 tests, which may increase the delay for other people's test results. It also may not, but again, SCC and all the other jurisdictions should know the sensitivity of delay vs number of tests. The optimal way to test twice, or four times, is undoubtedly different that the optimal way to test once.

More testing (say at 8 & 11 days) can give you a better idea of when the disease starts (if asymptomatic) so you can wait out your 10 days in isolation once you get a positive test.  If you test at 14 days and get a (first) positive, you will need to isolate until 24 days after exposure.  That's a long time when maybe you would have tested positive at day 6.

If she tested negative at 5 days and positive at 14 days, she should be counted as one that got it from a contact.  (Remember, she was in quarantine so she wasn't further exposed.)

I am assuming the SCC contacts to a case number includes anybody who tested positive within 14 days of their known exposures. Not sure that is true, but I think it is. Also, FWIW you can be further exposed in quarantine but not in isolation. In quarantine, you can be quarantined with other people. If one of them converts to positive, the quarantine starts over. It may be your relative quarantined alone, which would amount to isolation.