Performance of RT-PCR on saliva specimens compared to nasopharyngeal swabs for the detection of SARS-CoV-2 in children: A prospective comparative clinical trial

Abstract

BackgroundSaliva RT-PCR is an attractive alternative for the detection of SARS-CoV-2 in adults with much less known in children.MethodsChildren and adolescents with symptoms suggestive of COVID-19 were prospectively enrolled in a comparative clinical trial of saliva and nasopharyngeal (NP) RT-PCR between November and December 2020. Detection rates and sensitivities of saliva and NP RT-PCR were compared. Participants with discordant NP and saliva RT-PCR results including viral load (VL) were also analyzed.ResultOut of 405 patients enrolled, 397 patients had two tests performed. Mean age was 12.7 years (range 1.2-17.9). Detection rates were 22.9% (95%CI 18.8-27.1%) by saliva RT-PCR, 25.4% (21.2-29.7%) by NP RT-PCR, and 26.7% (22.4-31.1%) by any test. The sensitivity of saliva was 85.2% (78.2-92.1%) when using NP as the gold standard; in contrast, when saliva was considered the gold standard, the sensitivity of NP was 94.5% (89.8-99.2%).For a NP RT-PCR VL threshold of ≥103 and ≥104 copies/ml, sensitivity of saliva increases to 88.7% and 95.2% respectively. Sensitivity of saliva and NP swabs was respectively 89.5% and 95.3% in patient with symptoms less than 4 days (p=0.249) and 70.0% and 95.0% in those with symptoms ≥ 4 to 7 days (p=0.096). The 15 patients who had an isolated positive NP RT-PCR were significantly younger (p=0.034), had a lower NP VL (median 5.6×103 vs 3.9×107, p<0.001), and were not able to drool saliva at the end of the sampling (p=0.002). VLs were significantly lower with saliva PCR than with NP RT-PCR (median 8.7 cp/ml x104; IQR 1.2×104-5.2×105; vs median 4.0×107cp/ml; IQR 8.6×105-1.x108; p<0.001).ConclusionSaliva PCR shows diagnostic performances close to NP RT-PCR for SARS-CoV2 detection in most symptomatic outpatient children and adolescents.

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.…”

“…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).…”

Diagnostic Accuracy of SARS-CoV-2 Rapid Antigen Detection Testing in Symptomatic and Asymptomatic Children in the Clinical Setting

“…Finally, we did not evaluate the performance of P-RDT on oropharyngeal, nasal, or saliva specimens. However, given the fact that VL is lower in these anatomical compartments compared to NPS ( 24 – 27 ), one can expect even lower sensitivity of P-RDT if used on oropharyngeal, nasal, or saliva specimens.…”

Diagnostic accuracy of SARS-CoV-2 rapid antigen detection testing in symptomatic and asymptomatic children in the clinical setting

“…Finally, we did not evaluate the performance of P-RDT on oropharyngeal, nasal or saliva specimens. However, given the fact that VL is lower in these anatomical compartments when compared to NPS [21][22][23][24] , one can expect even lower sensitivity of P-RDT if used on oropharyngeal, nasal or saliva specimens.…”