ColoSSoS | Inter-laboratory Study

The Collaboration on Sewage Surveillance of SARS-CoV-2 (ColoSSoS) project combined the expertise of more than 50 Australian organisations in R&D activities that have enabled health departments across the country to integrate quantitative measurements of SARS-CoV-2 virus detected in sewage with human clinical PCR test data for COVID-19. This subproject investigated the accuracy and reliability of SARS-CoV-2 detection and quantification in sewage. One laboratory in New Zealand and 11 in Australia were given replicate samples of Sydney wastewater which did NOT contain SARS-CoV-2, a vial of dead SARS-CoV-2 virus, and Certified Reference Material that specified the ‘copy number concentrations of SARS-CoV-2 genome equivalents per mL’. Each laboratory added the dead virus to the Sydney sewage according to the same directions, then used their own, local methods to retrieve virus from the wastewater, extract its RNA and amplify and quantify sequences of RNA that are specific to the SARS-CoV-2 virus. In theory, each of the 12 sites could have made identical measurements, but in practice many factors affect recovery and measurement. It was therefore noteworthy that the protocols used by eight labs proved ‘fit-for-purpose’ and performed excellently, while this study identified areas for improvement in the remaining three labs.