Saliva as a testing sample for SARS-CoV-2 detection by RT-PCR in low prevalence community settings

Abstract

There is an urgency for the rapid and simple SARS-CoV-2 detection method. Our study aimed to demonstrate that saliva can be used as a specimen for SARS-CoV-2 detection notably for the screening of extensive population groups via pooling. We collected paired nasopharyngeal/oropharyngeal swabs (NPS) and saliva and performed 36 serial measurements of 8 SARS-CoV-2 positive saliva samples to confirm the stability of the specimen. We also completed 37 pools by adding one positive saliva specimen per pool. A field study including 3,660 participants was performed between September 29 and October 1, 2020. Saliva specimens were stable for testing for up to 24 hours. Overall, 1.2% of the saliva samples tested positive for SARS-CoV-2. The results of saliva samples were consistent with those obtained from NPS with 90% sensitivity (95% CI 68.3%-98.7%) and 100% specificity during the first two weeks after the onset of symptoms. All pools showed 100% positivity in different pooling proportions. Our findings demonstrate that saliva is an appropriate specimen for pooling and SARS-CoV-2 screening with accurate diagnostic performance. Patient-performed specimen collection allows testing an extensive number of people rapidly, obtaining results of the spread of SARS-CoV-2 and allowing authorities to take timely measures.

The accuracy of saliva versus nasopharyngeal and/or oropharyngeal samples for the detection of SARS-CoV-2 in children – A rapid systematic review and meta-analysis

“…103 papers were retained and assessed for full-text eligibility and 89 papers were excluded as they did not include children (individuals aged <18 years). Out of the 14 papers [8][9][10][11][12][13][14][15][16][17][18][19][20][21] which fulfilled our eligibility criteria, we requested additional accuracy data for 9 papers of which we obtained 5. The final 10 8,10-17,21 studies included in the meta-analysis comprised 5 studies for which data was received from authors and 5 studies where data was available in the original article.…”

“…The remaining six studies included both asymptomatic and symptomatic patients, but only one study 17 provided stratified data based on symptom status. All of the studies utilised nasopharyngeal swabs collected by healthcare workers as the comparator test except for two studies 10,14 which included nasopharyngeal and/or oropharyngeal swabs. Different techniques for saliva collection were used: general spitting technique in 5 studies 8,11,12,15,21 , drooling method in one study 13 , posterior oropharyngeal spitting technique (by asking children to clear their throats thoroughly and collect saliva) in one study 17 and 3 studies did not report the saliva collection technique 10,14,16 .…”

“…All of the studies utilised nasopharyngeal swabs collected by healthcare workers as the comparator test except for two studies 10,14 which included nasopharyngeal and/or oropharyngeal swabs. Different techniques for saliva collection were used: general spitting technique in 5 studies 8,11,12,15,21 , drooling method in one study 13 , posterior oropharyngeal spitting technique (by asking children to clear their throats thoroughly and collect saliva) in one study 17 and 3 studies did not report the saliva collection technique 10,14,16 . In addition to the usual saliva collection, one study collected saliva after oropharyngeal washing 12 (where patients were asked to gargle 2ml of saline solution 1-2 minutes prior to saliva collection).…”

Screening for SARS-CoV-2 by RT-PCR: Saliva or nasopharyngeal swab? Rapid review and meta-analysis

“…To prevent a shortage of analytic reagents and to cut the costs necessarily associated to mass screening strategies, several recent publications have proposed mass testing methods based on saliva sampling either through extraction-free protocols [ 76 – 78 ] or through pre-extraction sample pooling [ 79 – 81 ]. In addition, sample pooling has gained a recognized interest for recurrent screening programs from the Centres of Disease Control recommendations [ 82 ], and surveillance protocols implemented in higher education institutions across the world, e.g.…”