DIAGNOSTIC ACCURACY OF NON-INVASIVE DETECTION OF SARS-COV-2 INFECTION BY CANINE OLFACTION

BACKGROUNDThroughout the COVID-19 pandemic, testing individuals remains a key action. One approach to rapid testing is to consider the olfactory capacities of trained detection dogs. METHODSProspective cohort study in two community COVID-19 screening centers. Two nasopharyngeal swabs (NPS), one saliva and one sweat samples were simultaneously collected. The dog handlers (and the dogs...) were blinded with regards to the Covid status. The diagnostic accuracy of non-invasive detection of SARS-CoV-2 infection by canine olfaction was assessed as compared to nasopharyngeal RT-PCR as the reference standard, saliva RT-PCR and nasopharyngeal antigen testing. RESULTS335 ambulatory adults (143 symptomatic and 192 asymptomatic) were included. Overall, 109/335 participants tested positive on nasopharyngeal RT-PCR either in symptomatic (78/143) or in asymptomatic participants (31/192). The overall sensitivity of canine detection was 97% (95% CI, 92 to 99) and even reached 100% (95% CI, 89 to 100) in asymptomatic individuals compared to NPS RT-PCR. The specificity was 91% (95% CI, 72 to 91), reaching 94% (95% CI, 90 to 97) for asymptomatic individuals. The sensitivity of canine detection was higher than that of nasopharyngeal antigen testing (97% CI: 91 to 99 versus 84% CI: 74 to 90, p=0.006), but the specificity was lower (90% CI: 84 to 95 versus 97% CI: 93 to 99, p=0.016). CONCLUSIONSNon-invasive detection of SARS-CoV-2 infection by canine olfaction could be one alternative to NPS RT-PCR when it is necessary to obtain a result very quickly according to the same indications as antigenic tests in the context of mass screening.

Evaluation of saliva molecular point of care for detection of SARS-CoV-2 in ambulatory care

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.

Accuracy of antigen and nucleic acid amplification testing on saliva and naopharyngeal samples for detection of SARS-CoV-2 in ambulatory care

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.