Salivary SARS-CoV-2 RNA for diagnosis of COVID-19 patients: A systematic review and meta-analysis of diagnostic accuracy

Accurate, self-collected, and non-invasive diagnostics are critical to perform mass-screening diagnostic tests for COVID-19. This systematic review with meta-analysis evaluated the accuracy, sensitivity, and specificity of salivary diagnostics for COVID-19 based on SARS-CoV-2 RNA compared with the current reference tests using a nasopharyngeal swab (NPS) and/or oropharyngeal swab (OPS). An electronic search was performed in seven databases to find COVID-19 diagnostic studies simultaneously using saliva and NPS/OPS tests to detect SARSCoV-2 by RT-PCR. The search resulted in 10,902 records, of which 44 studies were considered eligible. The total sample consisted of 14,043 participants from 21 countries. The accuracy, specificity, and sensitivity for saliva compared with the NPS/OPS was 94.3 % (95 %CI = 92.1;95.9), 96.4 % (95 %CI = 96.1;96.7), and 89.2 % (95 %CI = 85.5;92.0), respectively. Besides, the sensitivity of NPS/OPS was 90.3 % (95 %CI = 86.4;93.2) and saliva was 86.4 % (95 %CI = 82.1;89.8) compared to the combination of saliva and NPS/OPS as the gold standard. Based on low to moderate certainty level these findings suggest a similarity in SARS-CoV-2 RNA detection between NPS/OPS swabs and saliva, and the association of both testing approaches as a reference standard can increase by 3.6 % the SARS-CoV-2 detection compared with NPS/OPS alone. This study supports saliva as an attractive alternative for diagnostic platforms to provide a non-invasive detection of SARS-CoV-2.

Automated summary

Accurate, self-collected, and non-invasive diagnostics are crucial for mass screening of COVID-19. This systematic review and meta-analysis evaluated the accuracy, sensitivity, and specificity of salivary diagnostics compared to nasopharyngeal and/or oropharyngeal swabs. The study found that using saliva for COVID-19 detection had an accuracy of 94.3%, specificity of 96.4%, and sensitivity of 89.2% compared to the reference tests. The findings suggest that saliva is a viable alternative for non-invasive SARS-CoV-2 detection.