SARS-CoV-2 viral load in the upper respiratory tract and disease severity in COVID-19 patients

Abstract

Due to the disease's broad clinical spectrum, it is currently unclear how to predict the future prognosis of patients at the time of diagnosis of coronavirus disease 2019 (COVID-19). Real-time reverse transcription-polymerase chain reaction (RT-PCR) is the gold standard molecular technique for diagnosing COVID-19. The number of amplification cycles necessary for the target genes to surpass a threshold level is represented by the RT-PCR cycle threshold (Ct) values. Ct values were thought to be an adequate proxy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load. A body of evidence suggests that SARS-CoV-2 viral load is a possible predictor of COVID-19 severity. The link between SARS-CoV-2 viral load and the likelihood of severe disease development in COVID-19 patients is not clearly elucidated. In this review, we describe the scientific data as well as the important findings from many clinical studies globally, emphasizing how viral load may be related to disease severity in COVID-19 patients. Most of the evidence points to the association of SARS-CoV-2 viral load and disease severity in these patients, and early anti-viral treatment will reduce the severe clinical outcomes.

Keywords: Severe acute respiratory syndrome coronavirus-2; Viral load; Upper respiratory tract; Coronavirus disease 2019 patients; Disease severity; Clinical outcome

Core Tip: Real-time reverse transcription-polymerase chain reaction is regarded as the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). Cycle threshold (Ct) values can be used to diagnose or forecast severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection since they are associated with virus load. Numerous differences exist in several clinical trials with small or large sample sizes, indicating a substantial positive correlation between the Ct value and disease severity in COVID-19. In this context, a literature review was conducted to address information gaps about the relationship between Ct levels and disease severity in COVID-19 patients globally. The majority of the data indicated a link between SARS-CoV-2 viral load and disease severity in these patients, and early anti-viral therapy will minimize the severity of the clinical outcomes.