The “false positive paradox” and the risks of testing
asymptomatic people for COVID-19
Widespread screening of asymptomatic people leads to high numbers of false positives when background prevalence is low, even with accurate tests. During the Covid-19 pandemic, not only has the background prevalence been low (vaccine clinical trial baseline testing finds 0.5-0.6% even during periods of higher prevalence), but the various COVID-19 tests are not very accurate. When inaccurate tests are combined with a low background prevalence, this results in a massive and unacknowledged problem of far more false positive test results than true positive test results, leading also to inaccurate characterization of COVID-19 hospitalizations and deaths.