Abstract
Background: No pathogen-specific prognostic biomarkers are yet
available for SARS-CoV-2. We sought to assess whether SARS-CoV-2 cycle
threshold value (Ct) at diagnosis may predict COVID-19 severity,
clinical manifestations and 6-month sequelae.
Methods: Hospitalised and outpatient cases were randomly
sampled from the diagnoses of March and data collected after 6 months by
interview and from the regional database for COVID-19 emergency.
Patients were stratified according to their RNA-dependent-RNA-polymerase
Ct in the nasal-pharyngeal swab at diagnosis: group A≤20.0,
20.0<B≤ 28.0, C>28.0. Disease severity was
classified according to a composite scale evaluating hospital admission,
worst oxygen support required and survival.
Results: One hundred sixty-eight survivors and thirty-two
deceased patients were included: 27.5% in A and B both, 45.0% in C.
90% of patients were symptomatic and 63.7% were hospitalised. Median
time from COVID-19 onset to swab collection was 5 days. Lethality,
number of comorbidities, disease severity, type and amount of signs and
symptoms, as well as 6-month sequelae inversely distributed among the
groups with respect to SARS-CoV-2 Ct. After adjusting for confounding,
SARS-CoV-2 Ct at diagnosis was still associated with COVID-19-related
death (p=0.023), disease severity (p=0.023), amount of signs and
symptoms (p<0.01) and presence of sequelae (p<0.01).
Conclusions: Early quantification of SARS-CoV-2 along the
course of the disease may be a useful predictive marker to inform
differential strategies of clinical management and resource allocation.
Keywords: COVID-19; Viral load; Sequelae; Outcomes; Cycle
threshold; Severity; Mortality