Always a concern, but under the present circumstances, a false positive (someone quarantines for two weeks who doesn't need it) is far better than a false negative (someone has false confidence in attending public places).

Unlike other false positives that could lead to unneeded/harmful interventions (surgery, chemo), erring on the side of false positives would actually be desirable for COVID-19.

I’d rather not be quarantined with a bunch of sick people for two weeks if I’m not actually sick. The risk of me getting the virus is much higher there than among the general populace. So I disagree that there are no downsides or risks for a false positive here. Especially as the disease has a chance to kill me.

Self-quarantine means they send you home and tell you not to leave for 2 weeks.

Unless you are in such an extreme case that you need a respirator or something, in which case they will hospitalize you and you might be around other diseased victims, but if you are in that condition then it is probably not a false positive. There is a shortage of hospital beds worldwide right now, so they are sending everyone home unless hospitalization is considered life-saving.

You quarantine at home.

All the restaurants and bars of California and New York are closing or are closed and all the people that work there are hourly wage. How how long do you think they will still have homes? Not trying to be alarmist but I also don’t see how people making an hourly wage are going to continue living in their very expensive states without income.

Unless the government backstops it, they won't. It is and will be a huge problem.

Some states are banning evictions for a few months, so at least there is that option. But it just means they'll be homeless in June instead of April.

Most NYC landlords have agreed to a 90-day hold on all evictions. So... about 90 days I guess.

You may have misheard the MD. The current tests have a very low false positive rate. That means if the test says you have Coronavirus, you have it. There's no "burden".

Where the tests are "not very accurate" is the false negative. The false negative rate can be as high as 50-60%, depending on tests and how it's administered. Sometimes they will conduct the test twice to improve accuracy.

The Roche ones recently approved have a lower negative test rate (10%?)

Edit: I removed my mention of 0% false positive rate because nothing in life is absolute.

> The current tests have a 0% false positive rate.

Need a citation on this. In order to even make a strong statement about the false positive rate you need to have some sort of alternate confirmation mechanism, usually clinical diagnosis or another more comprehensive test. That kind of work takes time and we haven't gotten to the point where we know this.

False positives in the test are one possible reason for the resurgence in Singapore; the initial screenings were overreporting the number of cases leading to a false sense of security, followed by a surge in real cases as the spread continued.

EDIT: A quick look at some of the tests available indicate that currently providers are not publishing specificity/sensitivity numbers in general under the accelerated release guidelines. One I did find was biomedomics test [1], which claims "The overall testing sensitivity was 88.66% and specificity was 90.63%", so ~10% of negative cases will show as positive.

[1] https://www.biomedomics.com/products/infectious-disease/covi...

That's an antibody-based test not approved for diagnostic use in the US, which is faster but less accurate than the RT-PCR ones currently being used.

It's just the only one that I could get numbers on. So... show me sensitivity/specificity numbers that show a 0% false positive rate. The CDC PCR test [1], for example, has some data and no false positives, but the sample sizes are so small (107 known negatives tested) that the best we can estimate is ~96% specificity.

[1] https://www.fda.gov/media/134922/download

"Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China." - https://link.springer.com/content/pdf/10.1007/s11427-020-166....

It seems asymptomatic patients can test negative multiple times on RT-PCR assays but be diagnosed other ways.

I've read somewhere that at least in China, the specificity of the PCR tests is only 60-70%, leaving ~30% undetected.

From the Discussion section of this paper: https://pubs.rsna.org/doi/10.1148/radiol.2020200642:

"According to current diagnostic criterion, viral nucleic acid test by RT-PCR assay plays a vital role in determining hospitalization and isolation for individual patients. However, its lack of sensitivity, insufficient stability, and relatively long processing time were detrimental to the control of the disease epidemic. In our study, the positive rate of RT-PCR assay for throat swab samples was 59% (95%CI, 56%-62%) which was consistent with previous report (30 - 60%) (6). In addition, a number of any external factors may affect RT-PCR testing results including sampling operations, specimens source (upper or lower respiratory tract), sampling timing (different period of the disease development) (6), and performance of detection kits. As such, the results of RT-PCR tests must be cautiously interpreted."

A 0% false positive rate is not possible. What if they switch your sample with someone else's while it's being handled by a human?

Edit:

>That means if the test says you have Coronavirus, you have it.

This line implies the parent comment is talking about the false positive rate of the entire testing process that results in you being told you're infected, not PCR as a platonic ideal, theoretical process.

That's still not a false positive rate of the test.

But I agree that 0% false positive rates are going to be nearly impossible to achieve (for just about anything that isn't mathematics).

From the FDA itself. Note how firm they are in regards to a positive, vs how cautious they are in regards to a negative. If you have COVID-19 RNA in your body...you have the virus.

What does it mean if the specimen tests positive for the virus that causes COVID-19? A positive test result for COVID-19 indicates that RNA from SARS-CoV-2 was detected, and the patient is infected with the virus and presumed to be contagious

What does it mean if the specimen tests negative for the virus that causes COVID-19? A negative test result for this test means that SARSCoV-2 RNA was not present in the specimen above the limit of detection. However, a negative result does not rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions. A negative result does not exclude the possibility of COVID-19.

https://www.fda.gov/media/135662/download

> A positive test result for COVID-19 indicates that RNA from SARS-CoV-2 was detected, and the patient is infected with the virus

You still haven't addressed the possibility of a protocol error such as a switched sample. The lab test itself may never produce false positives, but that emphatically does not mean that if the lab test comes back positive there is a 100% guarantee that the patient is infected.

Considering the context that I replied to is "we should also be aware of the danger of false positives", I think given the FDA source I posted (and what I've read elsewhere) I can say that there is absolutely no need to be aware of a danger of false positives in terms of disrupting people's lives.

If you want to argue on the fact of life that nothing in life is absolute. Fine. you win. If administered properly, and the test kit detects a presence of COHVID-19 RNA in your body, and the person telling you the results is not drunk, then the results is as close as 0% as practical.

That’s a protocol fault and has nothing to do with the accuracy of the test

Still better to have as one of many screening options