The Relationship Between Covid-19 Viral Load and Disease Severity: A Systematic Review Publisher Pubmed



Dadras O¹ ; Afsahi AM² ; Pashaei Z³ ; Mojdeganlou H⁴ ; Karimi A⁵ ; Habibi P³ ; Barzegary A⁶ ; Fakhfouri A⁶ ; Mirzapour P³ ; Janfaza N⁷ ; Dehghani S⁵ ; Afroughi F^{6, 8} ; Dashti M⁹ ; Khodaei S³ Show All Authors
Source: Immunity# Inflammation and Disease Published:2022

Abstract

Introduction: Patients with COVID-19 may present different viral loads levels. However, the relationship between viral load and disease severity in COVID-19 is still unknown. Therefore, this study aimed to systematically review the association between SARS-CoV-2 viral load and COVID-19 severity. Methods: The relevant studies using the keywords of “COVID-19” and “viral load” were searched in the databases of PubMed, Scopus, Google Scholar, and Web of Science. A two-step title/abstract screening process was carried out and the eligible studies were included in the study. Results: Thirty-four studies were included from the initial 1015 records. The vast majority of studies have utilized real-time reverse transcription-polymerase chain reaction of the nasopharyngeal/respiratory swabs to report viral load. Viral loads were commonly reported either as cycle threshold (Ct) or log10 RNA copies/ml. Conclusion: The results were inconclusive about the relationship between COVID-19 severity and viral load, as a similar number of studies either approved or opposed this hypothesis. However, the studies denote the direct relationship between older age and higher SARS-CoV-2 viral load, which is a known risk factor for COVID-19 mortality. The higher viral load in older patients may serve as a mechanism for any possible relationships between COVID-19 viral load and disease severity. There was a positive correlation between SARS-CoV-2 viral load and its transmissibility. Nonetheless, further studies are recommended to precisely characterize this matter. © 2021 The Authors. Immunity, Inflammation and Disease published by John Wiley & Sons Ltd.