SARS-CoV-2 respiratory viral loads and association with clinical and biological features

To determine the distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) respiratory viral loads (VL) during the acute phase of infection and their correlation with clinical presentation and inflammation-related biomarkers. Nasopharyngeal swabs from 453 adult SARS-CoV-2-infected patients from the Department of Infectious Diseases, Besançon, France, were collected at the time of admission or consultation for reverse transcriptase polymerase chain reaction (RT-PCR) analysis. Clinical information and concentrations of biological parameters (C-reactive protein [CRP], fibrinogen, lactate dehydrogenase [LDH], prealbumin) were noticed. Mean respiratory VL homogeneously decreased from 7.2 log₁₀ copies/ml (95% confidence interval [CI]: 6.6-7.8) on the first day of symptoms until 4.6 log₁₀ copies/ml (95% CI: 3.8-5.4) at day 10 (slope = -0.24; R²  = .95). VL were poorly correlated with COVID-19 symptoms and outcome, excepted for dyspnea and anosmia, which were significantly associated with lower VL (p < .05). CRP, fibrinogen, and LDH concentrations significantly increased over the first 10 days (median CRP concentrations from 36.8 mg/L at days 0-1 to 99.5 mg/L at days 8-10; p < .01), whereas prealbumin concentrations tended to decrease. Since SARS-CoV-2 respiratory VL regularly decrease in the acute phase of infection, determining the level of VL may help predicting the onset of virus shedding in a specific patient. However, the role of SARS-CoV-2 VL as a biomarker of severity is limited.