ABSTRACT
COVID-19 is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus affecting the world population. Early detection has become one of the most successful strategies to alleviate the epidemic and pandemic of this contagious coronavirus. Surveillance testing programs have been initiated in many countries worldwide to prevent the outbreak of COVID-19. In this study, we demonstrated that our previously established clustered regularly interspaced short palindromic repeats (CRISPR)-Cas12a-based assay could detect variants of concern during 2021 in Thailand, including Alpha, Beta, and Delta strains as well as Omicron strain in early 2022. In combination with the newly designed saliva collection funnel, we established a safe, simple, economical, and efficient self-collection protocol for the COVID-19 screening process. We successfully utilized the assay in an active case finding with a total number of 578 asymptomatic participants to detect the SARS-CoV-2 in saliva samples. We finally demonstrated that the validation and evaluation in a large-scale setting could provide valuable information and elaborate the practicality of the test in real-world settings. Our optimized protocol yielded effective results with high sensitivity, specificity, and diagnostic accuracy (96.86%). In addition, this study demonstrates COVID-19 active case findings in low-resource settings, which would be feasible and attractive for surveillance and outbreak prevention in the future.