key: cord-322724-7l1668bf
authors: Challener, Douglas; Shah, Aditya; O'Horo, John C.; Berbari, Elie F.; Binnicker, Matthew J.; Tande, Aaron
title: In Reply - Repeated testing in SARS-CoV-2 infection
date: 2020-08-10
journal: Mayo Clin Proc
DOI: 10.1016/j.mayocp.2020.08.006
sha: 
doc_id: 322724
cord_uid: 7l1668bf

nan

To The Editor: We appreciate the points raised by Lippi et al regarding our article describing repeat testing for SARS-CoV-2 infection. 1 In summary, the authors emphasize that repeat testing may be helpful in improving the negative predictive value of testing and ensuring that cases of COVID-19 are identified. The authors include evidence supporting the conclusion that identification of the SARS-CoV-2 virus is directly related to the number of nasopharyngeal swabs that are collected and also emphasize the importance of case-finding in control of the pandemic. In general, we agree that repeat testing may be helpful in certain situations of ongoing high suspicion for active infection where alternative approaches are not feasible; however, we believe that testing should not be applied indiscriminately in a resource-constrained situation.

Several studies have suggested that the number of unique patient specimens tested for SARS-CoV-2 is directly related to the positive identification of the virus and that there may be a high false-negative rate of molecular testing. 2, 3 The study by Zhang et al reported 41 hospitalized patients with an initial negative PCR test who had at least one positive result on subsequent testing. However, the timing between tests was not reported in this manuscript, which raises the possibility that some of the patients could have become infected following their first test. No laboratory test has 100% sensitivity, and we agree that the likelihood of detecting infected individuals will increase if they are tested more frequently. This characteristic of laboratory testing is not unique to SARS-CoV-2, but could be applied to molecular testing for many other infectious diseases. However, widespread indiscriminant repeat testing is not currently possible.

Unfortunately, supply chain challenges continue to limit the widespread availability of SARS-CoV-2 PCR testing in the United States. Tests should be used in an efficient manner and guided by principles of diagnostic stewardship. 4 We agree that there may be a role for repeat testing in patients with high clinical suspicion of 

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

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

FALSE-NEGATIVE RESULTS OF INITIAL RT-PCR ASSAYS FOR COVID-19: A SYSTEMATIC REVIEW

Mayo Clinic Strategies for COVID-19 Diagnostic Stewardship: An Essential Element in a Rapidly Evolving COVID-19 Pandemic

COVID-19 Testing: The Threat of False-Negative Results

 5 These strategies, in combination with strategic use of repeat testing will preserve limited resources and provide the best route towards ending the SARS-CoV-2 pandemic.