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

Objectives: Studies comparing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA load in the upper respiratory tract (URT) between children and adults-who either presented with corona virus disease 2019 (COVID-19) or were asymptomatic-have yielded inconsistent results. Here, we conducted a retrospective, single-centre study to address this issue. Patients and methods: Included were 1184 consecutive subjects (256 children and 928 adults) testing positive for SARS-CoV-2 RNA in nasopharyngeal exudates (NPs); of these, 424 (121 children and 303 adults) had COVID-19 and 760 (135 children and 625 adults) were asymptomatic close contacts of COVID19 patients. SARS-CoV-2 RNA testing was carried out using the TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, MS, USA). The AMPLIRUN (R) TOTAL SARS-CoV-2 RNA Control (Vircell SA, Granada, Spain) was used for estimating SARS-CoV-2 RNA loads (in copies/mL). SARS-CoV-2 RNA loads at the time of laboratory diagnosis (single specimen/patient) were used for comparison purposes. Results: Median initial SARS-CoV-2 RNA load was lower (p 0.094) in children (6.98 log10 copies/mL, range 3.0-11.7) than in adults (7.14 log(10) copies/mL, range 2.2-13.4) with COVID-19. As for asymptomatic individuals, median SARS-CoV-2 RNA load was comparable (p 0.97) in children (6.20 log(10) copies/mL, range 1.8-11.6) and adults (6.48 log10 copies/mL, range 1.9-11.8). Children with COVID-19 symptoms displayed SARS-CoV-2 RNA loads (6.98 log10 copies/mL, range 3.0-11.7) comparable to those of their asymptomatic counterparts (6.20 log(10) copies/mL, range 1.8-11.6) (p 0.61). Meanwhile in adults, median SARS-CoV-2 RNA load was significantly higher in symptomatic (7.14 log10 copies/mL, range 2.2-13.4) than in asymptomatic subjects (6.48 log(10) copies/mL, range 1.9-11.8) (p < 0.001). Overall, the observed URT SARS-CoV-2 RNA clearance rate was faster in children than in adults. Conclusions: Based on viral load data at the time of diagnosis, our results suggest that SARS-CoV-2-infected children, with or without COVID-19, may display NP viral loads of comparable magnitude to those found in their adult counterparts. However, children may have shorter viral shedding than adults. (C) 2021 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study revealed that children have similar viral loads to adults, but may have a shorter duration of viral shedding.