Upper respiratory tract SARS-CoV-2 RNA loads in symptomatic and asymptomatic children and adults

Costa, R.; Bueno, F.; Albert, E.; Torres, I.; Carbonell-Sahuquillo, S.; Barres-Fernandez, A.; Sanchez, D.; Padron, C.; Colomina, J.; Lazaro-Carreno, M. I.; Breton-Martinez, J. R.; Martinez-Costa, C.; Navarro, D.

Objectives: There is limited information comparing SARS-CoV-2 RNA load in the upper respiratory tract (URT) between children and adults, either presenting with COVID-19 or asymptomatic. Here we conducted a retrospective, single center study involving a large cohort of SARS-CoV-2 infected individuals to address this issue. Patients and Methods: A total of 1,184 consecutive subjects (256 children and 928 adults) testing positive for SARS-COV-2 RNA in nasopharyngeal exudates (NP) were included, of whom 424 (121 children and 303 adults) had COVID-19 not requiring hospitalization and 760 (135 children and 625 adults) were asymptomatic close contacts of COVID-19 patients. SARS-CoV-2 RNA testing was carried out using the TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, MS, USA). The AMPLIRUN TOTAL SARS-CoV-2 RNA Control (Vircell SA, Granada, Spain) was used for estimating SARS-CoV-2 RNA loads (in copies/mL). Results: Median SARS-COV-2 RNA loads were comparable between adults and children with COVID-19 (7.14 log10 copies/ml vs. 6.98 log10 copies/ml; P=0.094). Median SARS-CoV-2 RNA load in asymptomatic children and adults was similar (6.20 log10 copies/ml vs. 6.48 log10 copies/ml; P=0.97). Children with COVID-19 symptoms displayed SARS-CoV-2 RNA loads comparable to their asymptomatic counterparts (P=0.61). Meanwhile in adults, median SARS-CoV-2 RNA load was significantly higher in symptomatic than in asymptomatic subjects (P=<0.001), yet comparable (P=0.61) when the analysis excluded patients sampled within 48 h after symptoms onset. Conclusions: The data suggest that children may be drivers of SARS-CoV-2 transmission in the general population at the same level as adults.