Genemarkers is using the Thermo Fisher Scientific TaqPath® Covid-19 Kit for detection of the COVID-19 virus. This kit has Emergency Use Authorization (EUA) clearance from the Federal Drug Administration (FDA; 1,2). Genemarkers validation included analysis of clinical control samples provided by the State of Michigan Department of Health Laboratory. There was a 100% concordance in validation for all 30 samples tested. Analytical parameters tested in Genemarkers validation protocol were aligned with the Thermo Fisher kit expectations. The kit is highly sensitive with respect to analytical sensitivity; if viral RNA is present in the sample, it is very likely to be detected. However, either due to sampling error or the biology of the disease (e.g. virus present in lower but not upper respiratory tract), there have been known cases of patients with negative RT-PCR results who later were RT-PCR positive. The frequency of this (i.e. the clinical sensitivity) has not yet been determined. In published literature, one case series of 51 patients showed a sensitivity of RT-PCR of 71% from the first throat swab or sputum. 23% of those initial negatives were positive on the 2nd RT-PCR, 4% on the 3rd, and 2% on the 4th RT-PCR test (3). Another study conducting serial RT-PCR testing showed the mean time from an initial negative RT-PCR to subsequent positive RT-PCR was 5.1 days (± 1.5 days; 4).