Is saliva collected passively without forceful coughing sensitive to detect SARS-CoV-2 in ambulatory cases? A systematic review

Abstract

Objectives This systematic review was conducted to assess the sensitivity rate of SARS-CoV-2 detection in the saliva of ambulatory asymptomatic and mildly symptomatic patients, with saliva being collected passively without any forceful coughing. Study Design Literature search performed from January 2020 to July 2021. Prospective studies excluding letters to editors were included in our review only if saliva and nasopharyngeal samples were collected simultaneously, and sensitivity was reported using RT-PCR in asymptomatic or mildly symptomatic ambulatory cases. Results 436 studies were assessed; 10 (4 cohorts and 6 cross-sectional) studies met our inclusion criteria. The sensitivity rate of saliva to detect SARS-CoV-2 varied from 85.7% to 98.6% in all except in three studies. Lower sensitivity levels were attributed to low viral load (51.9%, 63.8%) or lack of supervision while collecting saliva (66.7%). Conclusion Passively collected saliva in the absence of coughing has a high sensitivity rate to detect SARS-CoV-2 in asymptomatic and mildly symptomatic patients when compared to nasopharyngeal swabs. Limitations of previous studies, such as lack of attention to the method of saliva collection, stages, and severity of the disease at the time of sample collection, can be researched in future investigations.

Parents’ and Childcare Workers’ Perspectives Toward SARS-CoV-2 Test and Surveillance Protocols in Pre-school Children Day Care Centers: A Qualitative Study Within the German Wü-KiTa-CoV Project

“…The present analysis is in line with this finding: parents believing that the procedure would be challenging for their child choose not to participate in the intervention. Considering that saliva tests have already shown to be highly accurate in detecting SARS-CoV-2 (16)(17)(18), our findings strengthen with insightful patient-centered data the existing guideline recommendations to perform saliva tests, instead of more invasive procedures, in children under 12 years of age (19). Besides non-invasive procedures, a child-friendly environment, involvement of parents to motivate and prepare children in advance, and test teams with an appreciative attitude toward children were seen as facilitating factors to implement the surveillance protocols in young children.…”

Recent advances in RNA sample preparation techniques for the detection of SARS-CoV-2 in saliva and gargle

“…Procedures for collecting saliva and gargle samples differ between studies. Different studies employed varying abstention times (15–60 min) of patients from eating, drinking, chewing gum, or smoking prior to saliva and gargle collection [ 23 , 32 ]. A longer abstention time before sample collection allows individuals to accumulate more viruses in the mouth.…”

“…Clear saliva samples collected by passive drooling or chewing on parafilm exhibited high clinical sensitivities for the detection of SARS-CoV-2 ranging from 87.3% to 95% relative to NPS [ 44 , 45 ]. Passively collected saliva samples without any forceful coughing had good clinical sensitivity, ranging from 85.7% to 98.6% in asymptomatic and mildly symptomatic patients [ 32 ]. The supernatant of saliva was found to contain higher SARS-CoV-2 RNA than saliva sediment and resuspended saliva [ 46 ].…”