Assessing nasopharyngeal (NP) swabs with nucleic acid amplification testing (NAAT) is considered the gold standard for detecting SARS-CoV-2, but proper sample collection requires trained personnel and is uncomfortable. Saliva, by contrast, is easily self-collected.
In a meta-analysis and systemic review, researchers evaluated NAAT testing of saliva versus NP swab specimens. Sixteen studies were included; of these, 10 exclusively tested outpatients and 2 involved population screenings in which participants were not required to show symptoms of COVID-19.
In all, 5,922 subjects underwent NAAT testing of saliva and NP swabs; 4,981 had negative tests for both samples and 941 had positive tests for one or both samples. The pooled sensitivity and specificity was 83.2% and 99.2%, respectively (saliva), and 84.8% and 98.9% (NP swab). Similar results were seen in a sensitivity analysis limited to outpatients undergoing a single test with each assay.
Routine serial screening for SARS-CoV-2 is central to a comprehensive strategy for controlling the pandemic in universities and other settings where social distancing is difficult to achieve. This study provides evidence that using easy-to-collect saliva specimens rather than NP swabs will not significantly compromise such efforts.