Quantifying SARS-CoV-2 viral load: current status and future prospects

ABSTRACT

Introduction: The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged as a novel viral agent that quickly spread worldwide. SARS-CoV-2 is responsible for the human coronavirus disease 2019 (COVID-19) which has claimed hundreds of thousands of lives and had an immeasurable toll on the economy. Currently, most clinical cases are identified by qualitative molecular testing. However, the need for quantitative assessment is gaining traction.

Areas covered: In this review, the current state and future perspective of SARS-CoV-2 viral load quantification is presented.

Expert opinion: Viral load quantification is a critical measure that informs clinicians of treatment response, actionable viral load levels, and guidance on patient management. Additionally, for pathogens with epidemiological consequences, viral load can provide information to guide infection control measures and policies. While qualitative detection is sufficient to identify cases and initiate containment and mitigation measures in the vast majority of COVID-19 cases, in certain situations, SARS-CoV-2 quantification is needed to assess viral load trending. However, there are obstacles to quantification, including variability in respiratory specimen collection and the lack of commutable reference material. At the same time, the need for quantification for clinical and epidemiological management is growing, especially concerning individuals with prolonged RNA shedding.

KEYWORDS:

• Molecular diagnostics
• COVID-19
• SARS-CoV-2
• viral load
• quantitative assay

Declaration of interest

MJ Lee has been a co-investigator for the NIH RADx-UP program; has received a one-time advisory fee from Roche Diagnostics; and has been an advisor for Resonantia Diagnostics. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

One peer reviewer has previously received travel grants from Pfizer Corporation and Astellas Pharma Corporation Limited and was an invited speaker for Gilead Sciences Limited and Luminex Corporation. Peer reviewers on this manuscript have no other relevant financial relationships or otherwise to disclose.

Additional information

Funding

This paper was not funded.