Dynamics of SARS-CoV-2 shedding in the respiratory tract depends on the severity of disease in COVID-19 patients

Abstract

A fraction of COVID-19 patients progress to a severe disease manifestation with respiratory failure and the necessity of mechanical ventilation. Identifying patients at risk is critical for optimized care and early therapeutic interventions. We investigated the dynamics of SARS-CoV-2 shedding relative to disease severity. We analyzed nasopharyngeal and tracheal shedding of SARS-CoV-2 in 92 patients with diagnosed COVID-19. Upon admission, standardized nasopharyngeal swabs or sputum were collected. If patients were mechanically ventilated, tracheal aspirates were additionally obtained. Viral shedding was quantified by real-time PCR detection of SARS-CoV-2 RNA. 45% (41 of 92) of COVID-19 had a severe disease course with the need for mechanical ventilation (severe group). At week 1, the initial viral shedding determined from nasopharyngeal swabs showed no significant difference between non-severe and severe cases. At week 2, a difference could be observed as the viral shedding remained elevated in severely ill patients. A time course of C-reactive-Protein (CRP), Interleukin-6 (Il-6), and Procalcitonin (PCT) revealed an even more protracted inflammatory response following the delayed drop of virus shedding load in severely ill patients. A significant proportion (47.8%) of patients showed evidence of prolonged viral shedding (>17 days), which was associated with severe disease courses (73.2%). We report that viral shedding does not differ significantly between severe and non-severe cases upon admission to the hospital. Elevated SARS-CoV-2 shedding in the second week of hospitalisation, a systemic inflammatory reaction peaking between second and third week and prolonged viral shedding are associated with a more severe disease course.