re: Louisiana COVID-19 - October 19, 2020 Update: +202 cases; +16 deaths; +3 hospitalized

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I'm sure it's been said BUT what is the false positive %? Sabans 3 negative tests after the positive got me wondering again

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1-2% (98-99% specificity, for the PCR testing). That said, the impact of false positives on overall numbers is a function of the “true” positivity rate, since you have to also factor in the 20-40% false negative rate (60-80% sensitivity). The lower the “true” positive rate, the larger the impact of false positives. If the true positivity rate is >5% or so (among those being tested) then the false negatives would be expected to outweigh the false positives. Below 5%, false positives outweigh the false negatives.

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And are there other viruses that a person can have but be asymptomatic (other than HIV I can't think of any off hand)??

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Tons. Something like 50% of influenza infections are asymptomatic.