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Comparison of Symptoms and RNA Levels in Children and Adults With SARS-CoV-2 Infection in the Community Setting

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Key Points

Question  How is the presence of symptoms associated with SARS-CoV-2 RNA levels in children vs adults in the community?

Findings  In this cross-sectional study of 555 children and adults with SARS-CoV-2 confirmed by reverse transcription–polymerase chain reaction, symptomatic individuals had higher SARS-CoV-2 RNA levels (as indicated by lower mean cycle threshold values) compared with asymptomatic individuals. No significant differences in RNA levels were found between asymptomatic children and asymptomatic adults or between symptomatic children and symptomatic adults.

Meaning  Regardless of age, in this community-based study, SARS-CoV-2 RNA levels were higher in symptomatic individuals.


Importance  The association between COVID-19 symptoms and SARS-CoV-2 viral levels in children living in the community is not well understood.

Objective  To characterize symptoms of pediatric COVID-19 in the community and analyze the association between symptoms and SARS-CoV-2 RNA levels, as approximated by cycle threshold (Ct) values, in children and adults.

Design, Setting, and Participants  This cross-sectional study used a respiratory virus surveillance platform in persons of all ages to detect community COVID-19 cases from March 23 to November 9, 2020. A population-based convenience sample of children younger than 18 years and adults in King County, Washington, who enrolled online for home self-collection of upper respiratory samples for SARS-CoV-2 testing were included.

Exposures  Detection of SARS-CoV-2 RNA by reverse transcription–polymerase chain reaction (RT-PCR) from participant-collected samples.

Main Outcomes and Measures  RT-PCR–confirmed SARS-CoV-2 infection, with Ct values stratified by age and symptoms.

Results  Among 555 SARS-CoV-2–positive participants (mean [SD] age, 33.7 [20.1] years; 320 were female [57.7%]), 47 of 123 children (38.2%) were asymptomatic compared with 31 of 432 adults (7.2%). When symptomatic, fewer symptoms were reported in children compared with adults (mean [SD], 1.6 [2.0] vs 4.5 [3.1]). Symptomatic individuals had lower Ct values (which corresponded to higher viral RNA levels) than asymptomatic individuals (adjusted estimate for children, −3.0; 95% CI, −5.5 to −0.6; P = .02; adjusted estimate for adults, −2.9; 95% CI, −5.2 to −0.6; P = .01). The difference in mean Ct values was neither statistically significant between symptomatic children and symptomatic adults (adjusted estimate, −0.7; 95% CI, −2.2 to 0.9; P = .41) nor between asymptomatic children and asymptomatic adults (adjusted estimate, −0.6; 95% CI, −4.0 to 2.8; P = .74).

Conclusions and Relevance  In this community-based cross-sectional study, SARS-CoV-2 RNA levels, as determined by Ct values, were significantly higher in symptomatic individuals than in asymptomatic individuals and no significant age-related differences were found. Further research is needed to understand the role of SARS-CoV-2 RNA levels and viral transmission.

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Article Information

Accepted for Publication: May 10, 2021.

Corresponding Author: Erin Chung, MD, University of Washington School of Medicine, Box 358061, 750 Republican St, Room E691, Seattle, WA 98109 (

Published Online: June 11, 2021. doi:10.1001/jamapediatrics.2021.2025

Author Contributions: Dr Chung had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Chung, Chow, Wilcox, Brandstetter, Adler, Lacombe, Rieder, Starita, Bedford, Englund, Chu.

Acquisition, analysis, or interpretation of data: Chung, Chow, Wilcox, Burstein, Brandstetter, Han, Fay, Pfau, Adler, Lacombe, Lockwood, Uyeki, Shendure, Duchin, Nickerson, Boeckh, Famulare, Hughes, Starita, Bedford, Englund, Chu.

Drafting of the manuscript: Chung, Chow, Wilcox, Brandstetter, Rieder, Englund, Chu.

Critical revision of the manuscript for important intellectual content: Chung, Chow, Wilcox, Burstein, Brandstetter, Han, Fay, Pfau, Adler, Lacombe, Lockwood, Uyeki, Shendure, Duchin, Nickerson, Boeckh, Famulare, Hughes, Starita, Bedford, Englund, Chu.

Statistical analysis: Wilcox, Pfau, Famulare, Hughes, Starita.

Obtained funding: Lacombe, Nickerson, Famulare, Starita, Bedford, Englund, Chu.

Administrative, technical, or material support: Burstein, Han, Fay, Adler, Lacombe, Lockwood, Shendure, Duchin, Rieder, Nickerson, Starita, Englund, Chu.

Supervision: Brandstetter, Lacombe, Boeckh, Starita, Bedford, Englund, Chu.

Conflict of Interest Disclosures: Drs Adler and Lockwood and Ms Lacombe report grants from the Bill and Melinda Gates Foundation during the conduct of the study. Dr Shendure is a consultant with Guardant Health, Maze Therapeutics, Camp4 Therapeutics, Nanostring, Phase Genomics, Adaptive Biotechnologies, and Stratos Genomics; and has a research collaboration with Illumina. Dr Boeckh is a consultant for Moderna, VirBio, and Merck; has received research support from Regeneron, Ridgeback, Merck, and VirBio outside the submitted work; and has received research support from the Bill and Melinda Gates Foundation during the conduct of the study. Dr Hughes reports grants from the Bill and Melinda Gates Foundation during the conduct of the study and National Institutes of Health outside the submitted work. Dr Bedford reports grants from the Bill and Melinda Gates Foundation, The Pew Charitable Trusts, and the National Institute of General Medical Sciences during the conduct of the study. Dr Englund receives research support paid to her institution from AstraZeneca, the Bill and Melinda Gates Foundation, Chimerix, GlaxoSmithKline, Novavax, Merck, and Pfizer; and is a consultant for Sanofi Pasteur and Meissa Vaccines. Dr Chu has served as a consultant with Ellume, Pfizer, the Bill and Melinda Gates Foundation, GlaxoSmithKline, and Merck; and has received research funding from Sanofi Pasteur and support and reagents from Ellume and Cepheid outside of the submitted work. No other disclosures were reported.

Funding/Support: This work was funded by the Bill and Melinda Gates Foundation. This work was supported in part by the National Institutes of Health (grant T32HD007233 to Dr Chung). Dr Bedford is a Pew Biomedical Scholar and is supported by National Institutes of Health grant R35 GM119774-01.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the funder.

Additional Contributions: We thank the study participants for their contribution of samples.

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