Prediction of Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infection by Quantitative Digital Polymerase Chain Reaction Normalized to International Units.

Although numerous studies have evaluated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection using cycle threshold (Ct) values as a surrogate of viral ribonucleic acid (RNA) load, few studies have used standardized, quantitative methods. We validated a quantitative SARS-CoV-2 digital polymerase chain reaction assay normalized to World Health Organization International Units and correlated viral RNA load with symptoms and disease severity.