SARS-CoV-2 in Sewage Treatment Works: Environmental Impact, Infectivity and Prevalence Modelling

Given that SARS-CoV-2 RNA is detectable in faeces for prolonged periods (even for otherwise asymptomatic individuals), efforts have so far concentrated on trying to map its prevalence using sewage samples, e.g. via our partners at Bangor University (NERC Urgency Grant NE/V004883/1). Because live viruses have also been detected in the stools of patients affected by COVID19, there is growing concern about the risks of faecal-oral transmission to humans and/or wildlife (where the virus first originated) via sewage outflows and overspill. This is particularly worrying as, for example, hundreds of tonnes of raw sewage enter the Thames each year when sewers overflow during rainstorms, effectively bypassing sewage treatment works (STWs) when they exceed capacity. We combine expertise from Life Sciences and Mathematics at Imperial College, corona virology at Nottingham University, and a network of collaborators to fill this gap and to complement ongoing work in related (but not overlapping) areas. We have also already secured £49K of internal funding from Imperial College to prime the lab work, as a direct in-kind contribution. First, the potential for sewage (via effluent discharge, storm overflows, and other forms of run-off) to contribute to transmission to humans and wildlife will be measured by assessing RNA concentration and viral infectivity from environmental samples, from sewage outflows down to rivers, estuaries, and faeces from wildlife. Second, using data on concentrations of SARS-CoV-2 RNA in sewage and in the environment, we will provide models of population-level prevalence of COVID19 and elucidate key environmental transmission routes for management.