key: cord-1056359-kupaueue
authors: Lippi, Giuseppe; Sanchis-Gomar, Fabian; Henry, Brandon M.
title: Repeated Testing in SARS-CoV-2 Iinfection
date: 2020-08-10
journal: Mayo Clin Proc
DOI: 10.1016/j.mayocp.2020.08.007
sha: ef914ce42eee5b4f2a9d4282ad09eaa34421d813
doc_id: 1056359
cord_uid: kupaueue

nan

To The Editor: In a recently published article in the journal, Challener et al. showed that 2.0% (i.e., 22/1113) of subjects tested positive within one week from the first negative nasopharyngeal swab for identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. 1 This evidence persuaded the authors to conclude that repeating an identical test in a low-prevalence environment is unlikely to generate added clinical value. However, some important considerations would lead us to disagree with this conclusion.

The fact that the SARS-CoV-2 identification is directly related to the number of subsequent nasopharyngeal swabs collected is now widely acknowledged. Zhang et al. 2 demonstrated that a 99% diagnostic sensitivity could be achieved after the fourth consecutive specimen collection. This suboptimal accuracy is attributable to a vast number of pre-analytical and analytical issues, which have been comprehensively reviewed elsewhere. 3 Besides these technical aspects, our perception is that a 2% rate of false-negative results on initial testing is not a negligible value and is not reassuring even (or especially) in a low-prevalence environment.

The underdiagnosis or delayed diagnosis of SARS-CoV-2 infection has been highlighted as an important reason for rapid spread of infection within the community. It has now been clearly established that the viral load of asymptomatic patients, which represent the vast majority of SARS-CoV-2 infections in low-prevalence areas, is almost identical to that of symptomatic patients. 4 This would imply that underdiagnosing these asymptomatic individuals would lead to a substantial risk of contagion and generation of new local outbreaks, especially in a low-prevalence scenario, where a perception of scarce virus circulation may have attenuated the degree of vigilance (i.e., social distancing, use of face masks, quarantine and so forth). From this perspective, a recent analysis carried out by Li and colleagues has highlighted that asymptomatic cases may have been J o u r n a l P r e -p r o o f

Low Utility of Repeat Real-Time PCR Testing for SARS-CoV-2 in Clinical Specimens

Distinct characteristics of COVID-19 patients with initial rRT-PCR-positive and rRT-PCR-negative results for SARS-CoV-2. Allergy

Potential preanalytical and analytical vulnerabilities in the laboratory diagnosis of coronavirus disease 2019 (COVID-19)

Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections

Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2)

Estimate of the Basic Reproduction Number for COVID-19: A Systematic Review and Meta-analysis

Rapid identification of SARS-CoV-2-infected patients at the emergency department using routine testing