Abstract
Saliva sampling could serve as an alternative non-invasive sample for SARS-CoV-2 diagnosis while rapid antigen tests (RATs) might help to mitigate the shortage of reagents sporadically encountered with RT-PCR. Thus, in the RESTART study we compared antigen and RT-PCR testing methods on nasopharyngeal (NP) swabs and salivary samples. We conducted a prospective observational study among COVID-19 hospitalized patients between 10 December 2020 and 1 February 2021. Paired saliva and NP samples were investigated by RT-PCR (Cobas 6800, Roche-Switzerland, Basel, Switzerland) and by two rapid antigen tests: One Step Immunoassay Exdia® COVID-19 Ag (Precision Biosensor, Daejeon, Korea) and Standard Q® COVID-19 Rapid Antigen Test (Roche-Switzerland). A total of 58 paired NP-saliva specimens were collected. A total of 32 of 58 (55%) patients were hospitalized in the intensive care unit, and the median duration of symptoms was 11 days (IQR 5-19). NP and salivary RT-PCR exhibited sensitivity of 98% and 69% respectively, whereas the specificity of these RT-PCRs assays was 100%. The NP RATs exhibited much lower diagnostic performance, with sensitivities of 35% and 41% for the Standard Q® and Exdia® assays, respectively, when a wet-swab approach was used (i.e., when the swab was diluted in the viral transport medium (VTM) before testing). The sensitivity of the dry-swab approach was slightly better (47%). These antigen tests exhibited very low sensitivity (4% and 8%) when applied to salivary swabs. Nasopharyngeal RT-PCR is the most accurate test for COVID-19 diagnosis in hospitalized patients. RT-PCR on salivary samples may be used when nasopharyngeal swabs are contraindicated. RATs are not appropriate for hospitalized patients.
Highlights
Rapid and accurate detection of SARS-CoV-2 infection in hospitalized patients is the cornerstone of prompt patient care and contact tracing
All patients with confirmed SARS-CoV-2 infection by NP real-time polymerase chain reaction (RT-PCR) and admitted in the intensive care unit (ICU) or internal medicine ward during the study period were screened for eligibility criteria
Saliva sampling is a promising alternative to NP swabs for SARS-CoV-2 diagnosis, given the ease of collection and comfort for repetitive testing as well as highly reliable results [2,3,4,5,6,9,10,11,12]
Summary
Rapid and accurate detection of SARS-CoV-2 infection in hospitalized patients is the cornerstone of prompt patient care and contact tracing. Swab real-time polymerase chain reaction (RT-PCR) remains the reference specimen for SARS-CoV-2 testing [1]. NP swabbing might expose healthcare workers to the risk of transmission during sampling and is a relatively invasive method, especially when. Microorganisms 2021, 9, 1910 considering the multiple samplings a patient will go through during a hospital stay. There is growing evidence advocating the role of salivary or oropharyngeal specimens as alternative non-invasive methods for SARS-CoV-2 diagnosis [2,3,4,5,6]. As a response to the growing SARS-CoV-2 pandemic and reagents shortages for rapid molecular systems, multiple rapid point-of-care tests (POCTs) have been added to the diagnostic pipeline for COVID-19 [7,8]. Current literature shows discordant results depending on the clinical setting studied, the sampling method or even whether a viral transport medium is used (VTM) [2,3,4,5,6,9,10,11,12,13,14,15,16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
