Association between SARS-CoV-2 Viral Load and Patient Symptoms and Clinical Outcomes Using Droplet Digital PCR

• Published in: Viruses Vol. 15; no. 2; p. 446
• Main Authors: Hastie, Elizabeth, Amogan, Harold, Looney, David, Mehta, Sanjay R
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-02-2023; MDPI
• Subjects: Brief Report; Clinical outcomes; Coronaviruses; COVID-19; COVID-19 - diagnosis; COVID-19 Testing; COVID-19 vaccines; Disease transmission; droplet digital PCR; Emergency medical care; Female; Fever; Humans; Immunization; Male; Measurement; Medical research; Medicine, Experimental; Middle Aged; Mortality; Pandemics; Polymerase Chain Reaction; Prediction models; RNA quantification; SARS-CoV-2 - genetics; SARS-CoV-2 viral load; Severe acute respiratory syndrome coronavirus 2; Statistical analysis; Veterans; Viral Load; Viremia; United States; United States > US; Basel Switzerland; Switzerland; COVID-19; droplet digital PCR; RNA quantification; SARS-CoV-2 viral load
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v15020446

The association between nasopharyngeal (NP) SARS-CoV-2 viral loads and clinical outcomes remains debated. Here, we examined the factors that might predict the NP viral load and the role of the viral load as a predictor of clinical outcomes. A convenience sample of 955 positive remnant NP swab eluent samples collected during routine care between 18 November 2020 and 26 September 2021 was cataloged and a chart review was performed. For non-duplicate samples with available demographic and clinical data (i.e., non-employees), an aliquot of eluent was sent for a droplet digital PCR quantification of the SARS-CoV-2 viral load. Univariate and multivariate analyses were performed to identify the clinical predictors of NP viral loads and the predictors of COVID-19-related clinical outcomes. Samples and data from 698 individuals were included in the final analysis. The sample cohort had a mean age of 50 years (range: 19-91); 86.6% were male and 76.3% were unvaccinated. The NP viral load was higher in people with respiratory symptoms (
= 0.0004) and fevers (
= 0.0006). In the predictive models for the clinical outcomes, the NP viral load approached a significance as a predictor for in-hospital mortality. In conclusion, the NP viral load did not appear to be a strong predictor of moderate-to-severe disease in the pre-Delta and Delta phases of the pandemic, but was predictive of symptomatic diseases and approached a significance for in-hospital mortality, providing support to the thesis that early viral control prevents the progression of disease.