[Goose]

That means that until we can test everyone, half of carriers may be going undetected.

I think it is important that the following be made clear once and for all. No country of any size is ever going to test everyone. Not now, not ever. Iceland started out with the stated goal of doing so. They immediately, if quietly, recognized that was impossible. They started a testing program in February. So far they have tested 17,900 people, or about 5% of the population of 364,000. At that rate, they could test their entire population in 1.66 years. Even if they could double or triple that rate, it wouldn't catch everybody because the people tested last month could now be positive by the next month.
The logistics of doing such an effort basically renders it impossible, even if testing materials and lab time didn't do so. Imagine the logistics of getting everybody to get their sample taken on the same day even with 364,000 people. Even in the same month would require processing 12,000 people a day every day. That would be possible if you could get the trained staff to do it, but nowhere I am aware of has that large a trained staff waiting to jump on it.
Iceland has shown that they can continue to function somewhat normally while containing the virus, as have Korea and Taiwan. The have done so without even coming close to testing everyone. Iceland is fortunate in that the population is somewhat homogeneous, the points of entry into the country are easily controlled, and they didn't have an initial large community spread. They have kept it that way by
"Testing and contact tracing are one of the key reasons why a lockdown has not been considered necessary up to this point," its Directorate of Health said in a statement to CNN.

"There is also another reason, no less important, we have pursued a very aggressive policy of quarantine for individuals -- suspected to be at risk of having contracted the virus -- for much longer and at a higher scale than most other countries we are aware of."

That latter statement is key. If the spread is under control, you have to keep it that way. To do so, some people are going to be really inconvenienced. Is the Bay Area getting ready to do that?

[Goose]

That means that until we can test everyone, half of carriers may be going undetected.

I think it is important that the following be made clear once and for all. No country of any size is ever going to test everyone. Not now, not ever. Iceland started out with the stated goal of doing so. They immediately, if quietly, recognized that was impossible. They started a testing program in February. So far they have tested 17,900 people, or about 5% of the population of 364,000. At that rate, they could test their entire population in 1.66 years. Even if they could double or triple that rate, it wouldn't catch everybody because the people tested last month could now be positive by the next month.
The logistics of doing such an effort basically renders it impossible, even if testing materials and lab time didn't do so. Imagine the logistics of getting everybody to get their sample taken on the same day even with 364,000 people. Even in the same month would require processing 12,000 people a day every day. That would be possible if you could get the trained staff to do it, but nowhere I am aware of has that large a trained staff waiting to jump on it.
Iceland has shown that they can continue to function somewhat normally while containing the virus, as have Korea and Taiwan. The have done so without even coming close to testing everyone. Iceland is fortunate in that the population is somewhat homogeneous, the points of entry into the country are easily controlled, and they didn't have an initial large community spread. They have kept it that way by
"Testing and contact tracing are one of the key reasons why a lockdown has not been considered necessary up to this point," its Directorate of Health said in a statement to CNN.

"There is also another reason, no less important, we have pursued a very aggressive policy of quarantine for individuals -- suspected to be at risk of having contracted the virus -- for much longer and at a higher scale than most other countries we are aware of."

That latter statement is key. If the spread is under control, you have to keep it that way. To do so, some people are going to be really inconvenienced. Is the Bay Area getting ready to do that?