SARS-CoV-2 Shedding Dynamics Across the Respiratory Tract, Sex, and Disease Severity for Adult and Pediatric COVID-19

BackgroundSARS-CoV-2 shedding dynamics in the upper (URT) and lower respiratory tract (LRT) remain unclear. ObjectiveTo analyze SARS-CoV-2 shedding dynamics across COVID-19 severity, the respiratory tract, sex and age cohorts (aged 0 to 17 years, 18 to 59 years, and 60 years or older). DesignSystematic review and pooled analyses. SettingMEDLINE, EMBASE, CENTRAL, Web of Science Core Collection, medRxiv and bioRxiv were searched up to 20 November 2020. ParticipantsThe systematic dataset included 1,266 adults and 136 children with COVID-19. MeasurementsCase characteristics (COVID-19 severity, age and sex) and quantitative respiratory viral loads (rVLs). ResultsIn the URT, adults with severe COVID-19 had higher rVLs at 1 DFSO than adults (P = 0.005) or children (P = 0.017) with nonsevere illness. Between 1-10 DFSO, severe adults had comparable rates of SARS-CoV-2 clearance from the URT as nonsevere adults (P = 0.479) and nonsevere children (P = 0.863). In the LRT, severe adults showed higher post-symptom-onset rVLs than nonsevere adults (P = 0.006). In the analyzed period (4-10 DFSO), severely affected adults had no significant trend in SARS-CoV-2 clearance from LRT (P = 0.105), whereas nonsevere adults showed a clear trend (P < 0.001). After stratifying for disease severity, sex and age (including child vs. adult) were not predictive of the duration of respiratory shedding. LimitationLimited data on case comorbidities and few samples in some cohorts. ConclusionHigh, persistent LRT shedding of SARS-CoV-2 characterized severe COVID-19 in adults. After symptom onset, severe cases tended to have higher URT shedding than their nonsevere counterparts. Disease severity, rather than age or sex, predicted SARS-CoV-2 kinetics. LRT specimens should more accurately prognosticate COVID-19 severity than URT specimens. Primary Funding SourceNatural Sciences and Engineering Research Council.