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Total and subgenomic RNA viral load in patients infected with SARS-CoV-2 Alpha, Delta, and Omicron variants
Journal article   Open access   Peer reviewed

Total and subgenomic RNA viral load in patients infected with SARS-CoV-2 Alpha, Delta, and Omicron variants

Derek E Dimcheff, Christopher N Blair, Yuwei Zhu, James D Chappell, Manjusha Gaglani, Tresa McNeal, Shekhar Ghamande, Jay S Steingrub, Nathan I Shapiro, Abhijit Duggal, …
The Journal of infectious diseases, Vol.228(3), pp.235-244
08/01/2023
DOI: 10.1093/infdis/jiad061
PMCID: PMC10420395
PMID: 36883903
url
https://doi.org/10.1093/infdis/jiad061View
Published (Version of record) Open Access

Abstract

SARS-CoV-2 genomic and subgenomic RNA levels are frequently used as a correlate of infectiousness. The impact of host factors and SARS-CoV-2 lineage on RNA viral load is unclear. Total nucleocapsid (N) and subgenomic N (sgN) RNA levels were measured by RT-qPCR in specimens from 3,204 individuals hospitalized with COVID-19 at 21 hospitals. RT-qPCR cycle threshold (Ct) values were used to estimate RNA viral load. The impact of time of sampling, SARS-CoV-2 variant, age, comorbidities, vaccination, and immune status on N and sgN Ct values were evaluated using multiple linear regression. Ct values at presentation for N (mean ±standard deviation) were 24.14±4.53 for non-variants of concern, 25.15±4.33 for Alpha, 25.31±4.50 for Delta, and 26.26±4.42 for Omicron. N and sgN RNA levels varied with time since symptom onset and infecting variant but not with age, comorbidity, immune status, or vaccination. When normalized to total N RNA, sgN levels were similar across all variants. RNA viral loads were similar among hospitalized adults, irrespective of infecting variant and known risk factors for severe COVID-19. Total N and subgenomic RNA N viral loads were highly correlated, suggesting that subgenomic RNA measurements adds little information for the purposes of estimating infectivity.
SARS-CoV-2 viral load variants of concern subgenomic RNA

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