Rapid salivary test suitable for a mass screening program to detect SARS-CoV-2: a diagnostic accuracy study

The study evaluates the diagnostic accuracy of a Rapid Salivary Test (RST) based on a lateral flow assay (LFA) for detecting SARS-CoV-2, with the goal of implementing a mass screening program. Conducted in an Italian hospital during the COVID-19 pandemic, 119 subjects provided both nasopharyngeal swabs and saliva samples for analysis. The RST demonstrated high sensitivity (93%) but moderate specificity (42%). Discrepancies between the RST and nasopharyngeal swabs were further analyzed using real-time reverse transcription PCR (rRT-PCR) on saliva samples. Notably, 57% of cases initially classified as false positives by RST were actually positive via salivary rRT-PCR, suggesting limitations in nasopharyngeal swab sensitivity. Observers also faced challenges in interpreting weak test signals, contributing to false positives. Despite its specificity limitations, the RST has potential for large-scale screening due to its rapid, non-invasive, and easily deployable nature. Future improvements in test readability and industrial-scale validation are planned to enhance its accuracy and utility in public health strategies against COVID-19.