Cycle Threshold to Test Positivity in COVID-19 for Return to Work Clearance in Health Care Workers
Sandra Domeracki, Robert N. Clapp, Kristopher Taylor, Chuanyi M. Lu, Harry Lampiris, Paul D. Blanc
Abstract
OBJECTIVE: To ascertain whether reverse transcriptase polymerase chain reaction (RT-PCR) cycle amplifications until detection, the cycle threshold (Ct), could help inform return to work (RTW) strategies for health care workers (HCWs) recovering from COVID-19 infection. METHODS: Sequential Ct data from COVID-19 nasal pharyngeal (NP) RT-PCR testing in all COVID-19 positive HCWs at a single institution. Analysis of Ct in relation to time until negative testing for RTW clearance. RESULTS: Data for 12 employees showed that time elapsed until RT-PCR test-based RTW clearance ranged from 7 to 57 days (median, 34.5 days). Lower initial Ct correlated with the total time elapsed until clearance (r = -0.80; P = 0.002). CONCLUSION: Considering the RT-PCR Ct, which correlates with the estimated viral load, may help inform RTW planning and decision making beyond solely relying on dichotomized positive/negative results.