Q&A: Antigen
Originally published:
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Antigen
Question
In light of the fact that antigen tests miss 47% of the sick, and also 37% of healthy people test positive for coronavirus, and given the base-rate problem, is it even worth taking the test?
Answer
With those figures (which I am not familiar with), the usefulness really does seem questionable. Especially if, when you go to get tested, you are already in a situation of suspicion, meaning there is a fairly good chance that you really are sick.
Discussion on Answer
Flip a coin instead of taking a test; the difference isn’t great.
Those numbers themselves are questionable. What I read was that 47% of those who were tested with an antigen test got a negative result, and then when tested afterward with PCR got a positive result. But you have to remember that a test taken a few days later will detect more positives because the illness had time to develop, and likewise, someone who got tested again is probably someone who developed symptoms and therefore suspected that the first test was wrong.
In short, the antigen test is probably less accurate, but not to that extent.