Dynamics of urinary and respiratory shedding of Severe acute respiratory syndrome virus 2 (SARS-CoV-2) RNA excludes urine as a relevant source of viral transmission

Purpose To investigate the expression of the receptor protein ACE-2 alongside the urinary tract, urinary shedding and urinary stability of SARS-CoV-2 RNA. Methods Immunohistochemical staining was performed on tissue from urological surgery of 10 patients. Further, patients treated for coronavirus disease (COVID-19) at specialized care-units of a university hospital were assessed for detection of SARS-CoV-2 RNA in urinary samples via PCR, disease severity (WHO score), inflammatory response of patients. Finally, the stability of SARS-CoV-2 RNA in urine was analyzed. Results High ACE-2 expression (3/3) was observed in the tubules of the kidney and prostate glands, moderate expression in urothelial cells of the bladder (0-2/3) and no expression in kidney glomeruli, muscularis of the bladder and stroma of the prostate (0/3). SARS-CoV-2 RNA was detected in 5/199 urine samples from 64 patients. Viral RNA was detected in the first urinary sample of sequential samples. Viral RNA load from other specimen as nasopharyngeal swabs (NPS) or endotracheal aspirates revealed higher levels than from urine. Detection of SARS-CoV-2 RNA in urine was not associated with impaired WHO score (median 5, range 3-8 vs median 4, range 1-8, p = 0.314), peak white blood cell count (median 24.1 x 1000/ml, range 5.19-48.1 versus median 11.9 x 1000/ml, range 2.9-60.3, p = 0.307), peak CRP (median 20.7 mg/dl, 4.2-40.2 versus median 11.9 mg/dl, range 0.1-51.9, p = 0.316) or peak IL-6 levels (median: 1442 ng/ml, range 26.7-3918 versus median 140 ng/ml, range 3.0-11,041, p = 0.099). SARS-CoV-2 RNA was stable under different storage conditions and after freeze-thaw cycles. Conclusions SARS-CoV-2 RNA in the urine of COVID-19 patients occurs infrequently. The viral RNA load and dynamics of SARS-CoV-2 RNA shedding suggest no relevant route of transmission through the urinary tract.

Automated summary

This study found high expression of ACE-2 receptor protein in the urinary system, and stable shedding of SARS-CoV-2 RNA in urine. Although viral RNA was detected in a small number of patients' urine samples, the study does not support a relevant route of virus transmission through urine.