Figure 2.
Relationship between β-actin and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection probability, stratified by illness severity. A mixed-effects binomial logistic regression relating SARS-CoV-2 detection to β-actin cycle threshold (Ct) value reveals a negative association, with high β-actin Ct (ie, low-quality) nasopharyngeal specimens less likely to detect SARS-CoV-2, across all strata of disease severity as assessed by chest radiography (A) or oxygen saturation (B). The absolute probability of SARS-CoV-2 detection is presented in relation to the observed range of β-actin Ct values. Abbreviations: Ct, cycle threshold; CT, computed tomography; O2, oxygen; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.