Saliva for molecular detection of SARS-CoV-2 in school-age children

The high diagnostic accuracy indices for saliva severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase PCR (RT-PCR) reported in adults has not been demonstrated in children, and adequately powered studies focused on the paediatric population are lacking. This study was carried out to determine the diagnostic accuracy of saliva for SARS-CoV-2 RT-PCR in ambulatory children.

During 1 to 23 October 2020, we recruited a population-based sample of children presenting for coronavirus disease 2019 (COVID-19) screening in Dubai, United Arab Emirates. Each child provided paired nasopharyngeal (NP) swab and saliva for SARS-CoV-2 RT-PCR N, E and RdRp gene detection.

Paired NP swab and saliva samples were obtained from 476 children with mean ± standard deviation age of 10.8 ± 3.9 years, and 58.2% were male (277/476). Nine participants were sampled twice, so 485 pairs of NP swab/saliva were tested. Virus detection in at least one specimen type was reported in 17.9% (87/485), with similar detection in NP swab (16.7%, 81/485) and saliva (15.9%, 77/485). Sensitivity and specificity of saliva RT-PCR was 87.7% (95% confidence interval (CI) 78.5-93.9) and 98.5% (95% CI 96.8-99.5). The positive and negative predictive values were 92.2% (95% CI 84.2-96.3) and 97.6% (95% CI 95.7-98.6), with a kappa coefficient of 0.879 (95% CI 0.821-0.937). Concordance of findings between NP swab and saliva did not differ by age (p 0.67) or gender (p 0.29). Cycle threshold (Ct) values were significantly higher in NP swab/saliva pairs with discordant findings compared to those with both specimens positive.

In light of these findings, we recommend saliva as a diagnostic specimen for COVID-19 screening in children.