Saliva Molecular Testing Bypassing RNA Extraction is Suitable for Monitoring and Diagnosing SARS-CoV-2 Infection in Children

• Main Author: Alenquer, M
• Publication Date: 2022
• Other Authors: Milheiro Silva, T, Akpogheneta, O, Ferreira, F, Vale-Costa, S, Medina-Lopes, M, Batista, F, Garcia, AM, Barreto, VM, Paulino, C, Costa, J, Sobral, J, Diniz-da-Costa, M, Ladeiro, S, Corte-Real, R, Delgado Alves, J, Leite, RB, Demengeot, J, Brito, MJ, Amorim, MJ
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.17/4175
• topic: Saliva molecular testing; SARS-CoV-2/diagnosis; Child; HDE INF PED

Background: Adults are being vaccinated against SARS-CoV-2 worldwide, but the longitudinal protection of these vaccines is uncertain, given the ongoing appearance of SARS-CoV-2 variants. Children remain largely unvaccinated and are susceptible to infection, with studies reporting that they actively transmit the virus even when asymptomatic, thus affecting the community. Methods: We investigated if saliva is an effective sample for detecting SARS-CoV-2 RNA and antibodies in children, and associated viral RNA levels to infectivity. For that, we used a saliva-based SARS-CoV-2 RT-qPCR test, preceded or not by RNA extraction, in 85 children aged 10 years and under, admitted to the hospital regardless of COVID-19 symptomatology. Amongst these, 29 (63.0%) presented at least one COVID-19 symptom, 46 (54.1%) were positive for SARS-CoV-2 infection, 28 (32.9%) were under the age of 1, and the mean (SD) age was 3.8 (3.4) years. Saliva samples were collected up to 48 h after a nasopharyngeal swab-RT-qPCR test. Results: In children aged 10 years and under, the sensitivity, specificity, and accuracy of saliva-RT-qPCR tests compared to NP swab-RT-qPCR were, respectively, 84.8% (71.8%-92.4%), 100% (91.0%-100%), and 91.8% (84.0%-96.6%) with RNA extraction, and 81.8% (68.0%-90.5%), 100% (91.0%-100%), and 90.4% (82.1%-95.0%) without RNA extraction. Rescue of infectious particles from saliva was limited to CT values below 26. In addition, we found significant IgM positive responses to SARS-CoV-2 in children positive for SARS-CoV-2 by NP swab and negative by saliva compared to other groups, indicating late infection onset (>7-10 days). Conclusions: Saliva is a suitable sample type for diagnosing children aged 10 years and under, including infants aged <1 year, even bypassing RNA extraction methods. Importantly, the detected viral RNA levels were significantly above the infectivity threshold in several samples. Further investigation is required to correlate SARS-CoV-2 RNA levels to viral transmission.