08/05/2020 Virus Transmission & Evolution

SARS-CoV-2 in human wastewater

By implementing a strict social distance policy, Portugal was able to minimize novel coronavirus impact in the community, gaining critical time to prepare for the unknown, while simultaneously ensuring access to a high quality public health care system.

Viral transmission will only stop due to either some powerful treatment we do not yet hold, or by herd immunity and vaccination as often discussed. The latter implies that a significant percentage of the population will experience infection.

Current transmission contention phase is being followed by a second wave, the size of which strongly depends on our behavior in attempting to slowly restore a more normal daily activity.

Our success in leading this second wave will mainly depend on the accurate health risk assessment combined with informed decision-making. At the current viral infection rates whose R(T) is not steadily below 1, we will need to adapt our mid-/ long-term strategy by extending the existing toolkit of tests and development of new methods for tracing fast-spreading. We should be vigilant to infection clusters of variable size, covering from small to large numbers of infected individuals across multiple geographical regions and to the demography factors to be able to protect the most vulnerable.

A brief communication entitled ‘SARS-CoV-2 in wastewater: potential health risk, but also data source’ has been recently published in The Lancet, Gastroenterology & Hepatology. This communication not only suggests human wastewater contaminated with the novel coronavirus can be a potential health risk, but also highlights the power of testing human wastewater samples for the presence of viral RNA as a proxy to identify infection clusters from a high-level macro view.

The perspective of a large-scale human wastewater contamination with novel coronavirus calls for an increased attention in the control of wastewater decontamination and in the drinking water quality testing for the presence of viral RNA.

Carefully planned wastewater sample testing for the presence of viral RNA can be used for the detection of infection clusters as part of a multi-scale data analysis methodology. A strategic definition of sampling locations within the national wastewater transport network may guide the drill-down and follow-up of large size infection clusters. Wastewater samples can be collected at any wastewater transport hierarchy level, covering from single buildings up to entire city sections. Wastewater sample testing can complement individual testing by targeting large size clusters where individual testing may not be feasible, unveiling hidden clusters of asymptomatic individuals, with a method that minimizes inherent risks from direct sample collection, providing a complementary data source for fighting the novel coronavirus in the current pandemics.

Contributing Scientist and translation: Jorge Cardoso

Scientific paper: SARS-CoV-2 in wastewater: potential health risk, but also data source