I wouldn't say it's too sensitive (as we continue to see quite a few false negatives), however I do believe that people continue to shed viral particles for a considerable amount of time in some cases.

This is why the guidance has been to not retest for infection clearance after a 10-14 days. All of the people I've seen retested for one reason or another, after having been infected, have tested negative though.

it's too sensitive to suggest any sort of infectiousness

the rapid antigen test not sensitive enough on the other hand

we need a test that's tuned in to give a positive result in the infectiousness time frame

based on what I'm hearing from people in the field, you can come in with classic covid, clear viral pneumonia and test negative more often than not with the rapid antigen

it's getting a reputation as being kinda trash

I'd say it's too sensitive... it detects the virus in people who have been dead for 3 months and that never even had the test! That's pretty sensitive.

Ideally you'd want a test to be 100% sensitive and 100% specific, that is also fast, simple, and easy to do. Typically this is unachievable without spending an unrealistic amount of money. So the solution is to have a screening test that is very sensitive, but not very specific. And then have diagnostic tests that are very specific, but not as sensitive.

The idea being that the screening test may catch stuff that isn't really concerning, but it's better than missing someone with cancer, for example. Then, because the screening test is known to pick up false positives, you send anyone detected by the screenign test for a diagnostic test (which is typically more expensive and/or takes longer to perform, is more invasive, etc).

The antigen test appeared initially to give us some hopes of being that screening test with PCR being a back stop, but that appears to not be the case. Antigen tests meet all criteria for a screening test (speed, cost, ease of use, less invasive, etc), except for sensitivity.

So that leaves the question on whether we need to still rely on PCR as a primary test, or just increase antigen testing to possibly catch more people just by the shear volume of testing. Do we use a certain cycle threshold for influenza, or other viruses, that's different from COVID? Are you catching someone with a low viral load because they're on the upslope? Or the downslope?

TRM said:

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Quote:

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The main test used to diagnose coronavirus is so sensitive it could be picking up fragments of dead virus from old infections, scientists say.
Most people are infectious only for about a week, but could test positive weeks afterwards.
Researchers say this could be leading to an over-estimate of the current scale of the pandemic.
But some experts say it is uncertain how a reliable test can be produced that doesn't risk missing cases.
Prof Carl Heneghan, one of the study's authors, said instead of giving a "yes/no" result based on whether any virus is detected, tests should have a cut-off point so that very small amounts of virus do not trigger a positive result.
He believes the detection of traces of old virus could partly explain why the number of cases is rising while hospital admissions remain stable.

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What do you all say?

https://www.bbc.com/news/health-54000629

Paper: https://www.medrxiv.org/content/10.1101/2020.08.04.20167932v3.full.pdf

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The CDC has recommendations for release from isolation based on a covid test and based on symptoms. I suspect that the one based on symptoms is largely to release you from isolation faster if the original test was a false positive.

When I had it, I was told by someone from the local hospital that I would have to test negative twice in a row with more than 24 hours between tests before i could be released from isolation. I contacted the Texas Department of State Hospital Services and was told to go by the CDC's criteria based on symptoms, not further tests.

eric76 said:

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TRM said:

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Quote:

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The main test used to diagnose coronavirus is so sensitive it could be picking up fragments of dead virus from old infections, scientists say.
Most people are infectious only for about a week, but could test positive weeks afterwards.
Researchers say this could be leading to an over-estimate of the current scale of the pandemic.
But some experts say it is uncertain how a reliable test can be produced that doesn't risk missing cases.
Prof Carl Heneghan, one of the study's authors, said instead of giving a "yes/no" result based on whether any virus is detected, tests should have a cut-off point so that very small amounts of virus do not trigger a positive result.
He believes the detection of traces of old virus could partly explain why the number of cases is rising while hospital admissions remain stable.

---

What do you all say?

https://www.bbc.com/news/health-54000629

Paper: https://www.medrxiv.org/content/10.1101/2020.08.04.20167932v3.full.pdf

---

The CDC has recommendations for release from isolation based on a covid test and based on symptoms. I suspect that the one based on symptoms is largely to release you from isolation faster if the original test was a false positive.

When I had it, I was told by someone from the local hospital that I would have to test negative twice in a row with more than 24 hours between tests before i could be released from isolation. I contacted the Texas Department of State Hospital Services and was told to go by the CDC's criteria based on symptoms, not further tests.

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But you could potentially be out of isolation within 2 days of your initial positive test if you were to get results on those two negatives. This is the strategy we are using to bring our employees back that are asymptomatic.