Comparison of Saliva and Nasopharyngeal Swab Nucleic Acid Amplification Testing for Detection of SARS-CoV-2

Abstract

Testing is the cornerstone of a successful public health response to coronavirus disease 2019 (COVID-19). Nasopharyngeal sampling for nucleic acid amplification testing (NAAT) is the current noninvasive criterion standard diagnostic test. However, nasopharyngeal testing requires trained personnel and handling of a specially designed swab, and the technique cannot be easily or reliably performed in all populations (eg, children and quarantined individuals).¹ A test that can be self-administered would greatly increase the options for case identification in the community. Consequently, alternative sampling sites are being explored to allow broader deployment of testing, increased access in remote regions, and testing among underserviced populations who may have limited access to highly qualified testing personnel. Of the currently available routes for testing, salivary testing likely represents the most practical option because it avoids the inconvenience, discomfort, and required technical expertise of nasopharyngeal sampling and could potentially be broadly deployed in the community. To date, the results of studies on the diagnostic performance of saliva NAAT are conflicting.^2,3 Furthermore, other studies have relied on the assumption that the sensitivity and specificity of the nasopharyngeal swab is perfect, which is not the case.⁴ To summarize the evidence on saliva NAAT performance, we conducted a systematic review of the operating characteristics of saliva NAAT for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the diagnosis of COVID-19 using nasopharyngeal NAAT as the comparator. We performed a bayesian latent class meta-analysis that adjusts for the imperfect accuracy of the comparator.