Wuhan, Hubei

Microbiologists at research institute KWR conducted a series of RNA-analyses at municipal waste water treatment plants (WWTP) in the Netherlands. The analyses showed the presence of RNA gene fragments of the COVID-19 virus in incoming sewage water. According to KWR the screening of the COVID-19 virus at municipal waste water plants can be used to signal new outbreaks in advance and play an important role to follow the evolution of the pandemic.

 

RNA-analysis is a method to measure the presence of viruses through capturing virus particles and detect specific gene fragments. The method does not discriminate between inactive and infectious particles. The KWR microbiologists say they have not yet been able to quantify the presence of these fragments. Their first findings indicate that the concentration of the virus at the WWTP is low.  Currently researchers are examining all samples multiple times and are looking at the reproducibility of the results. Furthermore, they double check and focus on fragments of multiple genes, to strengthen their results about the presence of the virus. The detection of COVID-19 in the sewage water at the Dutch WWTP does not really come as a surprise. Sewage water contains many viruses and the detection of the new coronavirus from human faeces was to be expected. Study results released by Chinese microbiologists in 2005 showed that SARS-CoV RNA had been detected in the sewage water of Chinese hospitals where SARS-patients were treated.

 

KWR suggests the use of the RNA-analyses of the SARS-CoV-2 in sewage water as a tool to measure the virus circulation in cities or smaller municipalities. The concentration level of the virus can be an indicator for the number of virus infections in the population and can signal in advance a new outbreak, for instance when a lock down is lifted. Similarly, these analyses can help monitor the effect of measures put in place to mitigate the spreading of the pandemic, according to KWR.

Via Juan Lama

We report the stability of SARS-CoV-2 in different environmental conditions. We first determined the stability of SARS-CoV-2 at different temperatures. SARS-CoV-2 in virus transport medium (VTM; final concentration: ∼6.8 log TCID50/mL) was incubated for up to 14 days and then tested for its infectivity (Table A). The virus is highly stable at 4°C, but sensitive to heat. At 4°C, there was only ∼0.7-log unit reduction of infectious titre on Day 14. With the incubation temperature being increased to 70°C, the time for virus inactivation was reduced to 5 minutes. 

 

We further investigated the stability of this virus on different surfaces. In brief, a 5-µL droplet of virus culture (∼7.8 Log unit of TCID50/mL) was pipetted on a surface (Table B; ∼1cm2 per piece) and left at room temperature (22°C; Relative humidity: ∼65%). The inoculated objects retrieved at desired time points were immediately soaked with 200 µL of VTM for 30 minutes to elute the virus. No infectious virus could be recovered from printing and tissue papers after a 3-hour incubation, whereas no infectious virus could be detected from treated wood and cloth on Day 2. By contrast, SARS-CoV-2 was more stable on smooth surfaces. No infectious virus could be detected from treated smooth surfaces on Day 4 (glass and banknote) or Day 7 (stainless steel and plastic). Strikingly, a significant level of infectious virus could still be detected on the outer layer of a surgical mask on Day 7 (∼0.1% of the original inoculum).

 

We also tested the virucidal effects of disinfectants by adding 15 µL of SARS-CoV-2 culture (∼7.8 Log unit of TCID50/mL) to 135 µL of various disinfectants at working concentration (Table C). With the exception of a 5-min incubation with hand soap, no infectious virus could be detected after a 5-minute incubation at room temperature. In addition, we also found that SARS-CoV-2 is extremely stable in a wide-range of pH values at room temperature (pH3-10; Table D). Overall, SARS-CoV-2 can be highly stable in a favourable environment4 , but it is also susceptible to standard disinfection methods.

 

Published in medRxiv (March 27, 2020) :

https://doi.org/10.1101/2020.03.15.20036673

Via Juan Lama