Dynamics of Blood Viral Load is Strongly Associated with Clinical Outcomes in COVID-19 Patients: A Prospective Cohort Study.

The prevalence and clinical relevance of viremia in patients with coronavirus disease 2019 (COVID-19) are not well-studied. A prospective cohort study was designed to investigate blood viral load and clearance kinetics in 52 patients (median age, 62 years; 31 [59.6%] male) and explore their association with clinical features and outcomes based on a novel one-step reverse-transcription droplet digital PCR (RT-ddPCR). By using one-step RT-ddPCR, 92.3% (48/52) of this cohort was quantitatively detected with viremia. The concordance between the blood and oropharyngeal swab tests was 60.92% (53/87). One-step RT-ddPCR was tested with a 3.03% of false positive rate and lower 50% confidence interval of detection (LOD50) at 54.026 copies/ml plasma. In all critical patients, the blood viral load was not eliminated, while the general and severe patients showed similar ability to clear the viral load. The viral loads in critical patients were significantly higher than those in general and severe counterparts. Among the 52 patients, 30 (58%) were discharged from hospital. Among half of 30 discharged patients, blood viral load remained positive, of which 76.9% (10/13) completely cleared their blood viral load at follow-up. Meanwhile, none of their close contacts had the evidence of infection. Quantitative determination of blood viral test is of great clinical significance to the management of COVID-19 patients.