Pretty curious to know what the false negative rate is. With the most popular current test (nasopharyngeal RT-PCR), the false negative rate is very roughly 30%, which is already pretty awful. And if you get tested significantly before or after peak viral load, it’s way worse than 30% [1]. If you get a negative result, you can’t really trust it, it’s giving false confidence to literally millions that they don’t have COVID, when they do.
It sounds like this test is not quite as good? If it has, say, a 40-50% false negative rate, I don’t really care how cheap and fast it is, that sucks. These tests are all pretty useless if you’re pre-symptomatic, so they’re not good for screening anyways, and if I’m at peak symptoms, I want accuracy over speed. I took a nasopharyngeal RT-PCR test and got results the same day, that’s fast enough if it’s more accurate. But if the accuracy is equivalent, or very nearly so, then it’s quite interesting.
> SalivaDirect is highly sensitive and yields similar outcomes as NP swabbing.
Doesn’t sound far better? And really, when hyping up a new technology, if I hear “similar outcomes”, my BS detector says “a bit worse.”
With NP swabs, the main issue doesn’t seem to be poor technique, it’s more that samples reasonably often don’t contain enough virus to be detected by the PCR test, unless you’re timing is really perfect (i.e. about 3 days after first spring symptoms). From my readings it’s not necessarily the collectors fault, there just didn’t happen to be high viral load in the part of the body when the sample was collected. Probably similar for saliva? Though I don’t really know.
This is interesting. I recently had a throat swab test after a week of extreme fatigue, but at no time did they indicate that the negative result was anything but certain. I had imagined _some_ false negative rate, but not this high.
This is why I laugh when people quote the infection numbers. It is potentially up to 30% wrong or heck, even more... nobody knows... but there is also other reasons, like inaccurate deduplication when people get multiple rounds of tests because of the high false negative rate.
Oh and because it is false negative, it is worse than you think, not better.
It sounds like this test is not quite as good? If it has, say, a 40-50% false negative rate, I don’t really care how cheap and fast it is, that sucks. These tests are all pretty useless if you’re pre-symptomatic, so they’re not good for screening anyways, and if I’m at peak symptoms, I want accuracy over speed. I took a nasopharyngeal RT-PCR test and got results the same day, that’s fast enough if it’s more accurate. But if the accuracy is equivalent, or very nearly so, then it’s quite interesting.
[1] https://www.acpjournals.org/doi/10.7326/M20-1495#s1-M201495