SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome

The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at first patient's hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confirmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log(10) copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n=85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (>= 7.35 log(10) copies/mL, p=0.003) and second tertile (>= 8.27 log(10) copies/mL, p=0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the final multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age >= 70 years, SpO(2), neutrophils>7.5x10(3)/mu L, lactate dehydrogenase >= 300 U/L, and C-reactive protein >= 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome.

Automated summary

The study assessed the ability of nasopharyngeal SARS-CoV-2 viral load at first patient's hospital evaluation to predict unfavorable outcomes in COVID-19 patients. High viral loads were associated with unfavorable outcomes but were not independently predictive. Five other predictors were independently associated with increased odds of ICU admission and death.