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by mc32 2139 days ago
Because antigen are cheaper but have higher error rates, PCR tests are more expensive but more accurate. Some people, I think B Gates among them, are proposing making antigen available to everyone and expanding capacity to 30MM/week.

So this could illustrate some issues that people should bear in mind when considering the antigen policy.
2 comments
somewhereoutth 2139 days ago
A distinction needs to be made between test accuracy and test sensitivity. Antigen tests or similar rapid testing may not be as sensitive, so may only detect very high viral loads - but if they are cheap and easy enough to test daily then this is not a problem, so long as they are taken every day.

Apparently viral load ramps up really fast, like hours, until the immune response kicks in, and it is at that high titre that you are most infectious. If everyone tested everyday, and isolated on a positive, then this could all be over by Christmas.

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losvedir 2139 days ago
Errors in which sense? False positives like here, which can then be resolved with the better PCR test, are much less of a concern than false negatives.
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benzible 2139 days ago
In the current situation where it may take 10+ days to get a lab test (for non-governors), it is an issue. For a warehouse worker making minimum wage, 10 days of missed work could lead to financial ruin. If we get to a point where most screening is done via abundant cheap antigen tests and RT-PCR capacity is available for confirmation then this would be less of an issue.

My understanding was actually that antigen tests are far less sensitive relative to RT-PCR but have high specificity. If that's correct, then DeWine's false negative would be a relatively rare event. By the way this is an excellent podcast episode covering the topic: https://www.microbe.tv/twiv/twiv-640/

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babesh 2139 days ago
The concern is whether the elevated positive tests that we are seeing is due to false positives. This is probably the case if it is the antigen tests that were administered.

Thus there was/is an emphasis on positive test rates rather than number of positive tests. However this distinction probably has been hard to get across to the public at large.

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