Testing individual and pooled saliva samples for sars-cov-2 nucleic acid: a prospective study

Abstract

Control of the rapid spread of the SARS-CoV-2 virus requires efficient testing. We collected paired nasopharyngeal swab (NPs) and saliva samples from 303 subjects (52.8% symptomatic) at a drive-through testing center; 18% of whom tested positive. The NPs, salivas and five saliva pools were tested for SARS-CoV-2 RNA using the Aptima™ assay and a laboratory-developed test (LDT) on the Panther-Fusion™ Hologic® platform. The saliva sensitivity was 80% (LDT) and 87.5% (Aptima™) whereas that of NPs was 96.4% in both assays. The pooled saliva sensitivity of 72.7% (LDT) and 75% (Aptima™) was not significantly different of that of individual saliva testing. Saliva specimens appear to be suitable for sensitive non-invasive assays to detect SARS-CoV-2 nucleic acid; pooling them for a single test will improve laboratory throughput.

Keywords: COVID-19; Nasopharyngeal swabs; Pooling; RT-PCR; SARS-CoV-2; Saliva; TMA.

Fig. 1

IP2 (A) or IP4 Ct values (B) for paired NPs and saliva samples. Data are means + SD. ****P ≤ 0.0001 (Student's paired t test).

Fig. 2

IP2 (A) or IP4 Ct values (B) for asymptomatic and symptomatic individuals. Data are medians plus interquartile range (IQR). *P ≤ 0.05 **P ≤ 0.01 (Mann-Whitney U-test).

Fig. 3

IP2 (A) or IP4 Ct values (B) for paired positive NPs and saliva individuals and NPs positive only individuals. Data are medians and IQR. ****P ≤ 0.0001 ***P ≤ 0.001 (Mann- Whitney U-test).