Antibody Tests For Coronavirus Can Miss The Mark
The increased availability of COVID-19 antibody tests is not a panacea.
Many people are hoping to use the results of this test to prove that they have had the disease, and thus cannot be infected a 2nd time.
A Story on NPR's Morning Edition 4/15/20 "Antibody Tests For Coronavirus Can Miss The Mark "shows why just the results of the antibody test aren't enough.
These antibody tests may have a specificity as high at 95%.
Just looking at the specificity alone is not enough. You also have to look at the prevalence of the disease in the population that you are measuring.
Here is an example from the NPR Story. "Here's what would happen if you used a test with 90% specificity in a population in which only 1% of the people have coronavirus (1% prevalence) . Nobody knows for sure, but that could be the situation in many parts of the country. In that instance, more than 90% of the positive results would be false positives, and falsely reassuring.
I don't want to discount the importance of the antibody test, but the results you do get from this test should not be used in isolation.
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