Viral dynamics of SARS-CoV-2 infection and the predictive value of repeat testing

ABSTRACT

BackgroundSARS-CoV-2 infections are characterized by viral proliferation and clearance phases and can be followed by low-level persistent viral RNA shedding. The dynamics of viral RNA concentration, particularly in the early stages of infection, can inform clinical measures and interventions such as test-based screening. MethodsWe used prospective longitudinal RT-qPCR testing to measure the viral RNA trajectories for 68 individuals during the resumption of the 2019-20 National Basketball Association season. For 46 individuals with acute infections, we inferred the peak viral concentration and the duration of the viral proliferation and clearance phases. FindingsAccording to our mathematical model, we found that viral RNA concentrations peaked an average of 3.3 days (95% credible interval [2.5, 4.2]) after first possible detectability at a cycle threshold value of 22.3 [20.5, 23.9]. The viral clearance phase lasted longer for symptomatic individuals (10.9 days [7.9, 14.4]) than for asymptomatic individuals (7.8 days [6.1, 9.7]). A second test within 2 days after an initial positive PCR substantially improves certainty about a patients infection phase. The effective sensitivity of a test intended to identify infectious individuals declines substantially with test turnaround time. ConclusionsSARS-CoV-2 viral concentrations peak rapidly regardless of symptoms. Sequential tests can help reveal a patients progress through infection stages. Frequent rapid-turnaround testing is needed to effectively screen individuals before they become infectious.