The authors were interested in the early risk factors that determine the duration of SARS-CoV-2 shedding. They conducted a prospective study in which a cohort of 137 patients with confirmed COVID-19 were followed. Viral shedding was calculated as the interval between the day the patient was found to be SARS-CoV-2 positive to when they returned to negative. The median SARS-CoV-2 PCR-positive duration was 12 days for this cohort. Factors associated with a significantly shorter duration were: younger age (hazard ratio [HR] 0.658); non-severe symptoms (HR 0.653); higher counts of lymphocytes (HR 1.464), eosinophils (HR 1.514) and CD8+ T cells (HR 1.745); and lower levels of IL-6 (HR 0.664) and IL-10 (HR 0.631). Multivariate analyses identified the CD8+ T cell count as being the predominant risk factor for SARS-CoV-2 PCR-positive duration (HR 2.376). Therefore CD8+ T cell count appears to be an important risk factor for the duration that patients with SARS-CoV-2 infection remain PCR positive.
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