Time to SARS-CoV-2 PCR Clearance in Immunocompromising Conditions: Is Test-Based Removal From Isolation Necessary in Severely Immunocompromised Individuals?

Abstract

To determine the association between immunosuppression and time to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) clearance, we studied 3758 adults retested following initial SARS-CoV-2 infection. Cox proportional hazards models demonstrated delayed PCR clearance with older age, multiple comorbidities, and solid organ transplant but not by degree of immunocompromise. These findings challenge current retesting practices.

Keywords: SARS-CoV-2; coronavirus disease 2019 (COVID-19); disease severity; immunocompromised host; immunosuppression; polymerase chain reaction; virus shedding.

Graphical Abstract

Figure 1.

Cycle thresholds for SARS-CoV-2 PCR tests performed in the outpatient (A, B) and inpatient settings (C, D) with available data. Gray dashed lines represent literature-reported thresholds above which there is negligible likelihood of infectious virus (24 for E gene, 32 for N gene) [21, 22]. Each circle represents a single test (there may be multiple tests per individual), and color corresponds to immunocompromise category (A, C) or disease severity (B, D). Mean cycle thresholds refer to mean target 1 and target 2 values within an individual test on a single assay. All assays are displayed together here, except for the Abbott RealTime SARS-CoV-2 assay, which reports cycle number values that incorporate 2 targets into a single cycle number, which are generally lower than and not equivalent to cycle thresholds, and are therefore displayed separately in the supplementary figure. Abbreviations: ICU, intensive care unit; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome 2.