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... at the time of the test. Or there was a follow up?
by kgwgk 7y ago
... at the time of the test. Or there was a follow up?
- DennisP 7y agoAnd what were the false positive rates?
- andrewla 7y agoIf I could upvote this a million times I would. If 50% of those tested positive are asymptomatic, then a good first-order approximation is that the false positive rate is 2x the actual prevalence, and the results say very little about prevalence that actual hospitalizations don't say. People, and to a large degree the media, are putting a huge emphasis on testing, not always in a way sensitive to the essential difficulty of evaluating test accuracy, especially in epidemiological settings.
- ghastmaster 7y agoWould it be disingenuous to say that false positives in the current case fatality rate would bring the rate down because hospitals are using symptoms combined with PCR for deaths?
- ineedasername 7y agoFrom what I've heard, at least in some areas, a Covid test is often performed only after a (usually very fast) flu test is performed. So a death resulting from a person negative for flu but also false-positive for Covid would seem very unlikely. As would any death of this sort from a person who came up positive. Much more likely would be that false positives cluster among those with mild or no symptoms (with the mild symptoms instead coming from a more mundane infection) If false positives were pushing the published death rate up, it's important to remember there are also deaths among people infected but never tested that would be pushing the rate down. I don't know if they would cancel each other out though. I would however really like to see published data from the CDC about reported pneumonia deaths just prior to the "official" outbreak to see if there was an otherwise unexplained increase.
- ghastmaster 7y agoAgreed. It will be very nice to have more data. There are too many ifs right now.
- ghastmaster 7y agoAre false positives more prevalent in this type of testing than false negatives? Edit: Due to the sars-cov-1?
- DennisP 7y agoI don't know but the problem is more with low infection rates. Suppose you have 3% false positives and 3% false negatives, and 0.1% of people are infected. The false negatives will be 3% of 0.1%. The false positives will be 3% of 99.9%. You exaggerate your infection rate by about 30X even though the test is equally inaccurate in both directions.
- ghastmaster 7y agoFantastic explanation!
- nabla9 7y agoIn Vo they first tested everyone, then there was 14 day lockdown for those infected, then they tested them again. 6 of them were still positive.
- christkv 7y agoWell maybe positive but not necessarily able to infect. If they used PCR tests it could give positive on broken up inactivated viruses for awhile after you cleared the infection