RESUMO
BackgroundRapid identification of SARS-Cov-2 infected individuals is a cornerstone in strategies for the control of virus spread. The sensitivity of SARS-CoV-2 RNA detection by RT-PCR is similar in saliva and nasopharyngeal swab. Rapid molecular point-of-care tests in saliva could facilitate, broaden and speed up the diagnosis. Objectives and methodsWe conducted a prospective study in two community COVID-19 screening centers to evaluate the performances of a CE-marked RT-LAMP assay (EasyCoV) specifically designed for the detection of SARS-CoV2 RNA from fresh saliva samples, compared to nasopharyngeal RT-PCR (reference test), to saliva RT-PCR and to nasopharyngeal antigen testing. ResultsOverall, 117 of the 1718 participants (7%) were tested positive with nasopharyngeal RT-PCR. Compared to nasopharyngeal RT-PCR, the sensitivity and specificity of the RT-LAMP assay in saliva were 34% (95%CI: 26-44) and 97% (95%CI: 96-98) respectively. The performance was similar in symptomatic and asymptomatic participants. The Ct values of nasopharyngeal RT-PCR were significantly lower in the 40 true positive subjects with saliva RT-LAMP (Ct 25.9) than in the 48 false negative subjects with saliva RT-LAMP (Ct 28.4) (p=0.028). Considering six alternate criteria for reference test, including saliva RT-PCR and nasopharyngeal antigen, the sensitivity of saliva RT-LAMP ranged between 27 and 44%. ConclusionIn the ambulatory setting, the detection of SARS-CoV-2 from crude saliva samples with the RT-LAMP assay had a lower sensitivity than nasopharyngeal RT-PCR, saliva RT-PCR and nasopharyngeal antigen testing. Registration numberNCT04578509 Funding SourcesFrench Ministry of Health and the Assistance Publique-Hopitaux de Paris Foundation.
RESUMO
BackgroundNasopharyngeal sampling for nucleic acid amplification testing (NAAT) is the current standard diagnostic test for of coronavirus disease 2019 (COVID-19). However, the NAAT technique is lengthy and nasopharyngeal sampling requires trained personnel. Saliva NAAT represents an interesting alternative but diagnostic performances vary widely between studies. ObjectiveTo assess the diagnostic accuracy of a nasopharyngeal point-of-care antigen (Ag) test and of saliva NAAT for detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), as compared to nasopharyngeal NAAT. DesignProspective participant enrollment from 19 October through 18 December 2020. SettingTwo community COVID-19 screening centers in Paris, France. Participants1452 ambulatory children and adults referred for SARS-CoV-2 testing. InterventionsNAAT on a saliva sample (performed with three different protocols for pre-processing, amplification and detection of SARS-CoV-2) and Ag testing on a nasopharyngeal sample. MeasurementsPerformance of saliva NAAT and nasopharyngeal Ag testing. ResultsOverall, 129/1443 (9%) participants tested positive on nasopharyngeal NAAT (102/564 [18%] in symptomatic and 27/879 [3%] in asymptomatic participants). Sensitivity was of 94% (95% CI, 86% to 98%), 23% (CI, 14% to 35%), 94% (CI, 88% to 97%) and 96% (CI, 91% to 99%) for the nasopharyngeal Ag test and the three different protocols of saliva NAAT, respectively. Estimates of specificity were above 95% for all methods. Diagnostic accuracy was similar in symptomatic and asymptomatic individuals. LimitationsFew children (n=122, 8%) were included. ConclusionIn the ambulatory setting, diagnostic accuracy of nasopharyngeal Ag testing and of saliva NAAT seems similar to that of nasopharyngeal NAAT, subject to strict compliance with specific pre-processing and amplification protocols. Registration numberNCT04578509 Funding SourcesFrench Ministry of Health and the Assistance Publique-Hopitaux de Paris Foundation.
