Wastewater analysis for the surveillance of viruses is not a new concept. In fact, the World Health Organization (WHO) published guidelines in 2003 for the environmental surveillance of poliovirus circulation where they recommend sampling the inlets of sewage (wastewater) treatment plants. Additionally, wastewater analysis for emerging recombinant noroviruses has also been demonstrated.
There has been discussion amongst scientists in Europe, the US and Australia as to the potential of using wastewater analysis to provide further information at the sewer catchment level on COVID-19. A number of opinion papers have also been published suggesting this, as well as laboratories in the US offering COVID-19 analysis of wastewater samples. Colleagues in the Netherlands at KWR Water Research have detected COVID-19 in wastewater using a qualitative method.
Wastewater analysis for COVID-19, if feasible, could potentially be applied in a number of ways. It could be used to establish whether COVID-19 has infected a community and monitor for when the community is relatively free of COVID-19 (i.e. below what can be detected in wastewater). It could also allow the rate of infection to be monitored over time in a wastewater catchment. Analysis could potentially allow for establishing the extent of infection beyond those individuals that have been individually tested. Most importantly it may be a useful tool for monitoring spatio-temporal changes in infection and monitor the efficacy of measures put in place to “flatten the curve”. From an epidemiological perspective there is also the benefit in detecting if the virus is mutating out from epicentres or if new strains are introduced from external locations, and/or the frequency that this occurs.
For wastewater analysis to be effective we need to make sure that the samples being collected are representative of the sewer catchment community. We have learnt from testing wastewater for illicit drugs and other chemicals that this is very important. Being able to detect COVID-19 in wastewater at community infection rates that are meaningfully low would also be important in realising some of the benefits listed above. We would not advocate its use in isolation, but in combination with other measures, such as the testing of individuals. Importantly, we believe it important that any use of wastewater, should it be feasible, ought not to take resources away from the testing of individuals and be done when a clear benefit has been identified.
