Diagnostic accuracy of SARS-CoV-2 saliva antigen testing in a real-life clinical setting.

BACKGROUND

SARS-CoV-2 antigen tests with saliva facilitate examination in settings that lack trained personnel. However, little is known on the diagnostic accuracy in real-life clinical settings. Therefore, we studied the diagnostic accuracy of a saliva antigen test to diagnose SARS-CoV-2 infection in a primary/ secondary care testing facility.

METHODS

Individuals presented at a COVID-19 testing facility affiliated with a Swiss University Hospital were prospectively recruited (n=377). Saliva specimen was obtained, and the PCL Inc. COVID19 Gold antigen test was conducted in parallel with two real-time PCR.

RESULTS

RT-PCR was positive in 53 individuals, corresponding to a prevalence of 14.1% (missing material in one individual). The PCL saliva antigen test was positive in 22 individuals (5.8%), and negative in 354 (93.9%). The sensitivity of the saliva antigen test was 30.2% (95% confidence interval, CI, 18.3 to 44.3), both overall and in symptomatic individiduals. The specificity was 98.1% (96.0, 99.3).

CONCLUSIONS

The diagnostic accuracy of a SARS-CoV-2 saliva antigen test in a primary/ secondary care testing facility was remarkably lower compared to the manufacturers' specifications. Keywords Infections/*epidemiology/transmission; severe acute respiratory syndrome coronavirus 2 [Supplementary Concept]; COVID-19 diagnostic testing [Supplementary Concept] Background.