COVID: false negative PCR results over time
A recent study documented the pretty high incidence of false negative PCR test results for SARS-CoV-2 after the initial infection (see https://www.acpjournals.org/doi/10.7326/M20-1495 ) Details : -- 7 previously published studies provided data on PCR performance by time since symptom onset or SARS-CoV-2 exposure, from 1330 upper respiratory tract samples -- most studies did serial testing and required at least one positive PCR to consider a case confirmed -- the FDA reports the specificity of PCR for SARS-CoV-2 to be 100%, though in this analysis the researchers assumed 90%, given that many studies were done outside of the US, and there might have been variability of test performance Results : -- false-negative rates by day of infection (see upper part of graph below): -- day 1 of infection: 100% (100%-100%) -- day 4 of infection: 67% (27%-94%) -- day 5 of infect...