This article is a Preprint
Preprints are preliminary research reports that have not been certified by peer review. They should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Preprints posted online allow authors to receive rapid feedback and the entire scientific community can appraise the work for themselves and respond appropriately. Those comments are posted alongside the preprints for anyone to read them and serve as a post publication assessment.
Variation of SARS-CoV-2 viral loads by sample type, disease severity and time: a systematic review
Preprint
in English
| medRxiv
| ID: ppmedrxiv-20195982
ABSTRACT
BackgroundTo describe whether SARS-CoV-2 viral loads (VLs) and cycle thresholds (CTs) vary by sample type, disease severity and symptoms duration. MethodsSystematic searches were conducted in MEDLINE, EMBASE, BioRxiv and MedRxiv. Studies reporting individual SARS-CoV-2 VLs and/or CT values from biological samples. Paired reviewers independently screened potentially eligible articles. CT values and VLs distributions were described by sample type, disease severity and time from symptom onset. Differences between groups were examined using Kruskal-Wallis and Dunn s tests (post-hoc test). The risk of bias was assessed using the Joanna Briggs Critical Appraisal Tools. Results14 studies reported CT values, 8 VLs and 2 CTs and VLs, resulting in 432 VL and 873 CT data points. VLs were higher in saliva and sputum (medians 4.7x108 and 6.5x104 genomes per ml, respectively) than in nasopharyngeal and oropharyngeal swabs (medians 1.7x102 and 4.8x103). Combined naso/oropharyngeal swabs had lower CT values (i.e. higher VLs) than single site samples (p=<0.0001). CT values were also lower in asymptomatic individuals and patients with severe COVID-19 (median CT 30 for both) than among patients with moderate and mild symptoms (31.4 and 31.3, respectively). Stool samples were reported positive for a longer period than other specimens. ConclusionVLs are higher in saliva and sputum and in individuals who are asymptomatic of with severe COVID-19. Diagnostic testing strategies should consider that VLs vary by sample type, disease severity and time since symptoms onset. SummaryThis systematic review found a higher viral load in saliva and sputum than in nasopharyngeal swabs, in asymptomatic individuals and patients with severe COVID-19. Diagnostic testing strategies should consider the type of sample, disease severity and the time since symptoms onset.
cc_by_nc
Full text:
Available
Collection:
Preprints
Database:
medRxiv
Type of study:
Diagnostic study
/
Experimental_studies
/
Prognostic study
/
Rct
/
Review
/
Systematic review
Language:
English
Year:
2020
Document type:
Preprint