Comparative Evaluation of Rapid Salivary RT-LAMP Assay for Screening of SARS-CoV-2 Infection

Abstract

Background: Response to the COVID-19 outbreak calls for rapid and accurate diagnostic tests to control the pandemic outbreak. We aimed to evaluate saliva specimen as well as rapid RT-LAMP test for diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.Methods: This monocentric study screened outpatients that were either symptomatic or contact-cases of a COVID-19 confirmed case.Nasopharyngeal-swabs (NPS) and saliva were collected simultaneously and tested by RT-qPCR. Saliva samples were also analyzed using an extraction-free rapid RT-LAMP test (EasyCOV®). Infected participants were those with a positive (Ct value Findings: Between the 1st September and the 7th of October 2020, samples of 443 adults were collected and analyzed. The mean age was 32·2 years, 59·4% declared mild symptoms at the time of sampling and 40·6% were asymptomatic. Positivity rate of NP and/or salivary RT-qPCR was 16·0% (71/443) and the concordance between these two methods was 87·3%. Sensitivity and specificity of RT-LAMP compared to CRTest were 85·9% (95% CI 77·8%-94·0%) and 99·5% (98·7%-100%), respectively. RT-LAMP accuracy was 91·0% and 98·2% compared to NP and salivary RT-qPCR, respectively. All 52 participants with a salivary RT-qPCR Ct value Interpretation: We demonstrated that self-collected saliva and a rapid RT-LAMP-based field test are reliable alternatives for SARS-CoV-2 detection. Their use could complement, simplify and accelerate COVID-19 diagnostics.Clinical Trial Registration: NCT04337424Funding Statement: SkillCell, CNRS, Region OccitanieDeclaration of Interests: Dr. J Reynes reports personal fees from Gilead company, personal feesfrom ViiV Healthcare company, personal fees from MSD Company, personalfees from Pfizer Company, personal fees from TheratechnologiesCompany, outside the submitted work.Dr. F Molina reports grants from SkillCell ; personal fees fromSkillCell, outside the submitted work. In addition, Dr. Molina has apatent Patent # EP20166524 pending.Dr. J Espeut, Dr. J Baptiste and Dr. F Santos Schneider reportspersonal fees from SkillCell, outside the submitted workThe other authors declared no competing interest.Ethics Approval Statement: The study was approved by a French ethic committee (CPP-lle de France XI) on April 03, 2020 and a substantial modification was approved on May 11, 2020.