Diagnostic and monitoring utilities of saliva for SARS-CoV-2

Introduction Nasopharyngeal (NP) swab is an invasive procedure that is difficult to perform in pediatric cases and those with special needs. On the other hand, saliva has been a proposed sample given the ease of collection, comfort and the ability to self-collect. The research project aims to study the presence of SARS-CoV-2 in the saliva of suspected COVID-19 patients in comparison to its presence in NP swabs. Methodology A cross-sectional study was conducted in October 2020 in COVID19 clinic in the Bahrain Defense Force Hospital. The study compared the presence of SARS-CoV2 by PCR in saliva samples to nasopharyngeal samples. COVID-19 Clinic tests symptomatic, staff, close contacts and pre-operation patients. Results The saliva PCR has shown a sensitivity of 72.9% (95% CI: 58.2% - 84.7%) and a specificity of 98.8% (95% CI: 97.8% - 99.4%). The PPV was 74.5% (95% CI 59.7% to 86.1%) and the NPV was 98.6% (95% CI 97.7% to 99.3%). Kappa coefficient of agreement between saliva and NP was 0.723 (95% CI 0.62 to 0.82, p<0.001). Moreover, when restricting cases to symptomatic only, the sensitivity of saliva increased to 86.7% (95% CI 59.5% to 98.3%) while specificity remained high at 97.2%. Conclusion The findings of the study suggest that saliva samples have the potential to be used as a screening tool for SARS-CoV-2, especially in symptomatic individuals. This is especially important when it is difficult to collect NP samples. Saliva samples are however at risk of producing more false negative tests.