Saliva-Based Testing

Delayed detection of SARS-CoV-2 has been a major hindrance in curbing the current COVID-19 pandemic. Widespread testing is the most practical way out of the current crisis. The current gold standard for COVID-19 diagnosis is real-time reverse transcription polymerase chain reaction (RT-PCR) detection of SARS-CoV-2 from nasopharyngeal swabs. However, collecting nasopharyngeal swabs causes discomfort to patients due to the procedure’s invasiveness, limiting compliance for repeat testing, and the procedure presents a considerable risk to healthcare workers. Therefore, developing rapid and convenient ways of testing for COVID-19 will greatly enhance the capacity of testing. Alternatively, saliva is a promising candidate for SARS-CoV-2 diagnostics because (1) collection is minimally invasive and can reliably be self-administered and (2) saliva has exhibited comparable sensitivity to nasopharyngeal swabs in detection of SARS-CoV-2. Recently, saliva-based testing has been developed for use at testing sites or in a health care provider’s location, thus making it ideal for point-of-care or large-scale population testing.

Nasopharyngeal Swabs
Nasopharyngeal Swabs
Saliva Collection
Saliva Collection

The GVN promotes saliva-based testing to enhance efficient diagnostic of COVID-19, thus stopping a chain of viral transmission. Currently, some saliva test kits can be purchased, self-administered at home and then shipped to a designated lab for diagnostic (i.e., Spectrum, Rutgers, and P-23 At-home COVID-19 test collection kits). Users would receive their results through an app within 48 hours. In addition, available saliva-based testing is listed below based on literature review.

Available Saliva-Based SARS-CoV-2 Diagnostics

Assay Brief Protocol Reference
RT-LAMP•Optimized an inactivation protocol with improved success across heterogenous saliva samples •RNA extraction for saliva sample: a magnetic bead-based rapid RNA-purification procedure.Development of a saliva-optimized RT-LAMP assay for SARS-CoV-2 | medRxiv
RT-PCR•RNA extraction by using TRIzol (guanidinium thiocyanate/phenol-chloroform) •Detect minimal quantities of the SARS-CoV-2 using samples from both upper respiratory tract swabs (nasal and throat) as well as salivaPaz, S., et al. (2020) A simplified SARS-CoV-2 detection protocol for research laboratories. PLOS ONE. doi.org/10.1371/journal.pone.0244271.
A multiplex SARS-CoV-2 antibody immunoassay• Saliva and sera collected from confirmed coronavirus disease 2019 (COVID-19) cases for testing IgG, IgA, and IgM. •Saliva samples were collected by using saliva collection device (Malvern Medical Developments, UK).COVID-19 Serology at Population Scale: SARS-CoV-2-Specific Antibody Responses in Saliva (nih.gov)
rRT-PCR; Chemiluminescent (Lumipulse G); Point-of-care testing for for SARS-CoV-2 antigen detection.•Saliva was self-collected by the Salivette device (SARSTEDT AG & Co, Nümbrecht, Germany)•RNA extraction for saliva sample: a magnetic bead-based rapid RNA-purification procedure.Salivary SARS-CoV-2 antigen rapid detection: a prospective cohort study (medrxiv.org)
An aptamer-based SARS-CoV2 salivary antigen assay• Sample collection: matched nasopharyngeal swabs (NPS) in RNAShield DNA/RNA storage medium (Zymo) or viral transport medium and saliva samples (no additive) from symptomatic and asymptomatic study subjects • Viral RNA extraction using the MagMax Viral/Pathogen Nucleic Acid Isolation Kit (Thermo) and the TaqPath COVID-19 multiplex RTqPCR assay.Hitting the diagnostic sweet spot: Point-of-care SARS-CoV-2 salivary antigen testing with an off-the-shelf glucometer (medrxiv.org)
RT-LAMP• Non-hazardous chelating agent Chelex-100 to prepare saliva samples for RT-LAMP •RNA extraction for saliva sample: a magnetic bead-based rapid RNA-purification procedure.A simple direct RT-LAMP SARS-CoV-2 saliva diagnostic | medRxiv
RT-PCR and droplet digital PCR• Comparison of RNA extraction by using a TRIzol-based RNA extraction and QIAmp MinElute Virus DNA/RNA Spin Kit and QIAmp Viral RNA Mini Kit (CDC recommended). •Test kits worked better than TRIzol method•RNA extraction for saliva sample: a magnetic bead-based rapid RNA-purification procedure.Sensitive detection and quantification of SARS-CoV-2 in saliva | medRxiv