No correlation between Ct values and severity of disease or mortality in patients with COVID 19 disease

Abstract

There are several reports of Ct values of RT PCR assays for COVID 19 being associated with disease severity and infectivity. We studied the correlation between Ct values and disease severity and mortality at our hospital . All patients with RT PCR diagnosed COVID 19 illness admitted at the study site and for whom Ct values were available were included in the study. The patients with mild disease had significantly lower Ct values than patients with severe disease but had also been tested significantly earlier in the illness than those with severe disease. The patients who died had significantly lower Ct values than patients who survived but here again they had significantly shorter duration of symptoms before testing. We therefore recommend that the time of testing since onset of symptoms should be controlled for while correlating Ct values with disease severity.

Keywords: COVID-19; Cycle threshold; Mortality; SARS-CoV-2.