Back to my question about false negatives. Looks like they may cancel out the false positives.
https://www.clinicaloncology.com/COVID-19/Article/07-20/False-Negatives-Found-If-COVID-19-Testing-Done-Too-Soon/58781For the new analysis, Johns Hopkins Medicine researchers reviewed reverse transcriptase–polymerase chain reaction (RT-PCR) test data from seven prior studies, including two preprints and five peer-reviewed articles. The studies covered a combined total of 1,330 respiratory swab samples from a variety of people, including hospitalized patients and those identified through contact tracing in an outpatient setting.
Using RT-PCR test results, along with reported time of exposure to the virus or time of onset of measurable symptoms—such as fever, cough and breathing problems—the researchers calculated the probability that someone infected with SARS-CoV-2 would have a negative test result when they had the viral infection. In the published studies, health care providers collected nasal and throat samples from patients and noted the time of virus exposure or symptom onset and sample collection.
From these data, the Johns Hopkins researchers calculated daily false-negative rates. The researchers estimated that those tested with SARS-CoV-2 in the four days after infection were 67% more likely to test negative, even if they had the virus (CI, 27% to 94%). When the average patient began displaying symptoms of the virus, the false-negative rate was 38%. The test performed best eight days after infection (on average, three days after symptom onset), but even then had a false-negative rate of 20% (CI, 13% to 31%).
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