False Positive Rapid Test Policy

[elcapitanJack]

I haven't heard of any rapid tests I've administered having false positives, only many many false negatives. False positives aren't really a thing with most of the tests, though you may be in an area that uses different tests than we do.

Does many many false negatives mean the tests could be less than completely accurate?

 

[LolaNJoe]

Does many many false negatives mean the tests could be less than completely accurate?

Bearing in mind there are many different kinds of tests, the false negative rate for the test used in one of the hospital systems I work at is 40% with no false positives per our lab techs. That's also the typical false negative rate for the flu tests we've been using for years. For admissions testing negative we often will retest a few days later.

When you test also makes a difference. Your odds of getting a false negative are much, much higher within the first 72 hours of showing symptoms with that 40% dropping way down after that, though I can't recall exact numbers I believe it goes down to around15%. I would imagine an asymptomatic person would remain around the 40% false negative rate, which I believe can be due in part to viral load.

I wish I had more concrete data, but I'm not a lab tech and was told these stats several months ago (we have not changed tests since), and these are for rapid and not PCR tests. I'm an RN in an area that has seen a lot of covid.

 

[Marissa227]

I am a lab tech. Antigen tests DO have a false positive rate (as well as a false negative rate). We only report antigen tests as "Negative" or "Presumptive Positive" and "Presumptive Positive" tests reflex to a PCR for confirmation. We have three platforms for PCR in our lab, of which two can be run point-of-care and give out a result in 15-52 minutes. Some of the antigen tests are placed into a "reader" or a little device that detects whether or not there is a second line that develops (just like a pregnancy test). I have seen this "reader" call a test positive that looks negative to the naked eye and is then the individual is negative by PCR. I would hope they would have a point-of-care PCR instrument on hand to confirm any positive/presumptive positive antigen tests, but who knows. Hope that helps.

 

[dez1978]

The swab is the same and when I went to Walgreens for my self administered PCR test the instructions were also the same. Insert 1/2-3/4 inches up, swirl around with medium pressure for 15 seconds on each nostril, making sure to do at least 5 circles per side.

I've had 3 PCR tests done. 2 of them were administered by a medical person and they all went the same distance up my nose. Same as the Binax Now. The worst part is the stinging sensensation.

Thats not at all how it's done here. The PCR ones are the ones that go way up there and make your eyes water. The Binax now ones are just inside your nostril kind of where the bone starts. Our PCR ones are done off site here in town, by an outside company, but the first couple rounds were done by our nurses here. The Binax ones are done here daily, and we can swab ourselves. To date I've had 14 PCR tests and daily binax ones for a couple of months. I work at a psych hospital. About 1/2 of our staff have been trained to to the Binax tests due to the amount of testing we do.

 

[Marissa227]

Thats not at all how it's done here. The PCR ones are the ones that go way up there and make your eyes water. The Binax now ones are just inside your nostril kind of where the bone starts. Our PCR ones are done off site here in town, by an outside company, but the first couple rounds were done by our nurses here. The Binax ones are done here daily, and we can swab ourselves. To date I've had 14 PCR tests and daily binax ones for a couple of months. I work at a psych hospital. About 1/2 of our staff have been trained to to the Binax tests due to the amount of testing we do.

PCR with Abbott ID Now is a just nasal swab and is frequently used point-of-care. That's probably what DLgal had.