Wide application of minimally processed saliva on multiple RT-PCR kits for SARS-CoV-2 detection in Indonesia

Mahendra, C.; Kaisar, M. M. M.; Vasandani, S. R.; Surja, S. S.; Tjoa, E.; Chriestya, F.; Junusmin, K. I.; Widowati, T. A.; Irwanto, A.; Ali, S.

Saliva as a sample matrix has been an attractive alternative for the detection of SARS-CoV-2. However, due to potential variability in collection and processing steps, it is recommended to evaluate a proposed workflow amongst the local population. Here, we aim to validate collection and treatment of human saliva as a direct specimen for RT-qPCR based detection of SARS-CoV-2 in Indonesia. We demonstrated that SARS-CoV-2 target genes were detected in saliva specimen and remained stable for five days refrigerated or room temperature storage. The method of processing saliva specimen described in this report is free from RNA-extraction step, thereby reduces cost, time, and manpower required for processing samples. The developed method was validated for use on three COVID-19 RT-PCR kits commercially available. Our developed method achieved 85% agreement rate when compared to paired nasopharyngeal and oropharyngeal swab specimens (NPOP). With the assistance of a specimen sampling device, QuickSpit(TM), collection was found to be more convenient for individuals and improved agreement rate to 90%.