Quantitative association of SARS-CoV-2 in wastewater and clinically confirmed cases in different areas of the Tokyo 2020 Olympic and Paralympic Village.

International mass gathering events, such as the Olympic and Paralympic Games, face the risk of cross-border transmission of infectious diseases. We previously reported that wastewater-based epidemiology (WBE), which has attracted attention as a COVID-19 surveillance tool, was implemented in the Tokyo 2020 Olympic and Paralympic Village to gain a comprehensive understanding of COVID-19 incidence in the village. In the present study, we explored the quantitative association of wastewater viral load and clinically confirmed cases in various areas of the village. From July 14 through September 8, 2021, 360 passive samples and 329 grab samples were collected from seven distinct areas within the village through manholes and examined for SARS-CoV-2 RNA by the Efficient and Practical virus Identification System with Enhanced Sensitivity (EPISENS) methods. The detection rates of SARS-CoV-2 RNA in passive and grab samples showed a significant association (P < 0.001, φ = 0.32, chi-square test), with passive sampling showing higher positive rate. Based on the Receiver Operating Characteristic (ROC) curve analysis on the wastewater viral load and clinically confirmed cases, the most sensitive cutoff point was judged to be the limit of quantification (LOQ) for the passive three-day samples. Under this optimal condition, the sensitivity and specificity were 0.78 and 0.40, respectively. The present study demonstrated the effectiveness of passive sampling for building-level wastewater surveillance based on the quantitative analysis of wastewater viral load and reported cases. Wastewater surveillance can be a powerful tool to monitor the incidence of infectious diseases among temporary residents, such as tourists and participants in international mass gathering events, provided that proper analytical methods and quantitative cutoff point are employed.