COVID-19 faecal-oral transmission: Are we asking the right questions?

Detection of the SARS-CoV-2 virus in stools and sewage has recently been reported, raising the hypothesis of faecal-oral transmission. If confirmed, this could have far-reaching consequences for public health and for pandemic control strategies. In this paper, we argue that a comprehensive and more nuanced analysis is required to test this hypothesis, taking into consideration both environmental dynamics and the persistence of viral infectivity. First, we examine the evidence regarding the presence of the virus in stools and sewage. Then we discuss the current framework of disease transmission through water and excreta and how the transmission of a respiratory disease fits into it. Against this background, we propose a framework to test the faecal-oral hypothesis, unpacking the different environmental routes from faeces to the mouth of a susceptible person. This framework should not be seen as a confirmation of the hypothesis but rather as an expanded view of its complexities, which could help shaping an agenda for research into a number of unanswered questions. Finally, the paper briefly discusses practical implications, based on current knowledge, for containment of the pandemic.