Diagnostic performance, stability, and acceptability of self-collected saliva without additives for SARS-CoV-2 molecular diagnosis

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19), leading to a global pandemic. The molecular diagnosis of this virus is mostly performed by collecting upper respiratory samples, which has many disadvantages, including patient discomfort and the need for trained healthcare professionals. Although saliva has emerged as a more comfortable sample, the use of additives to preserve viral RNA is expensive and, in some cases, difficult for self-collection.

Method: This study evaluated the diagnostic performance by RT-PCR and stability of self-collected saliva using wide-mouth specimen collection cups without stabilization and/or inactivation buffers for SARS-CoV-2 detection, compared to nasopharyngeal samples and saliva collected with additives. Additionally, the study assessed the acceptability of this sample collection method among participants and healthcare personnel.

Results: The study included 1281 volunteers with a 24.6% positive infection rate. Saliva demonstrated comparable diagnostic performance to nasopharyngeal samples, with a sensitivity of 87.6% and specificity of 99.6%, for a total percent agreement of 96.4%. The study also showed that viral RNA in saliva remained stable for at least 72 h at different temperatures. Notably, saliva samples without additives exhibited a lower RdRp Ct compared to samples with additives, suggesting that the absence of stabilization and/or inactivation buffers does not significantly affect its performance. The study highlighted the acceptability of saliva among patients and healthcare personnel due to its noninvasive nature and ease of collection.

Conclusions: This research supports the implementation of self-collected saliva as a comfortable and user-friendly alternative sample for SARS-CoV-2 diagnosis.

Keywords: Acceptability; COVID-19; Performance; Saliva; Self-collection; Stability.