Concentration and detection of SARS coronavirus in sewage in China

Concentration and detection of SARS coronavirus in sewage in China. Spencer EA, Heneghan C.

Published on July 13, 2020

Reference Wang XW, Li J, Guo T, et al. Concentration and detection of SARS coronavirus in sewage from Xiao Tang Shan Hospital and the 309th Hospital of the Chinese People's Liberation Army. Water Sci Technol. 2005;52(8):213-221.  2020
Study type
Country China
Setting Sanitation system
Funding Details Non reported
Transmission mode Orofecal, Waterborne

Bottom Line

No live SARS-CoV was found in any sewage samples from two hospitals receiving COVID-19 patients. SARS-CoV RNA was detected in sewage concentrates of two hospitals receiving SARS patients prior to disinfection, and occasionally after disinfection.

Evidence Summary

The nucleic acid of SARS-CoV was identified by PCR in the sewage collected prior to disinfection of the hospitals. 

After disinfection of the hospitals, SARS-CoV RNA could be detected from some samples from the 309th Hospital of the Chinese People’s Liberation Army, but not from Xiao Tang Shan Hospital.

There was no live SARS-CoV detected in the sewage in these assays. 

In this study, the authors found that the virus can survive for 14 days in sewage at 4°C, 2 days at 20°C, and its RNA can be detected for 8 days although the virus had been inactivated. 

What did they do?

To confirm whether the sewage is a possible major transmission path of SARS-CoV or not, a novel style of electropositive filter media particle was used to concentrate the SARS-CoV from the sewage of hospitals receiving SARS patients in Beijing of China, and cell culture and RT–PCR were used to detect and identify the viruses from sewage. 

Study reliability

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes No N/A N/A Unclear

What else should I consider?

The study authors suggested three reasons for the lack of live virus being found in any sewage sample:

  1. the SARS-CoV-2 was killed by the high concentration of disinfectants used after patient had a bowel movement; 
  2. the quantity of SARS-CoV was insufficient to be detected by the current methods; 
  3. SARS-CoV-2 may lose its infectivity by some unknown factors.

The total residual chlorine varied from 0 mg/L to 1.0 mg/L, and free residual chlorine from 0 mg/L to 0.5 mg/L in sewage from Xiao Tang Shan Hospital; from the 309th Hospital, the total residual chlorine varied from 3.0 mg/L to 12.5 mg/L, and free residual chlorine from 1.5 mg/L to 5.0 mg/L. 

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.