The relentless impact of the COVID-19 pandemic has profoundly strained healthcare infrastructures and economic systems across the globe, exposing the vulnerabilities of society’s most at-risk populations, particularly residents in long-term care facilities (LTCFs). Throughout the pandemic, the fundamental importance of early detection and proactive treatment became evident, reliably mitigating hospitalization rates, lowering mortality, and substantially reducing healthcare costs. Against this backdrop, wastewater surveillance at treatment plants (WSTPs) has emerged as a cutting-edge, cost-effective methodology capable of providing early warnings by detecting viral outbreaks within the sewage of entire communities. Despite its adoption in numerous developed countries, Japan has been notably conservative in integrating this surveillance technology at scale.
A recent pioneering study led by Professor Byung-Kwang Yoo of Waseda University’s Faculty of Human Sciences and Professor Masaaki Kitajima from the Research Center for Water Environment Technology at The University of Tokyo undertook an economic evaluation of a city-level warning system pivoting on wastewater surveillance. Their research—soon to be published in the esteemed journal Science of The Total Environment—proposes a novel framework wherein the detection of surges in COVID-19 viral loads through wastewater analysis could trigger timely clinical testing interventions, particularly targeting LTCFs. This initiative aims to bridge gaps in Japan’s public health monitoring systems by leveraging data-driven insights from wastewater samples for more informed policy-making.
Intriguingly, the proposed warning system draws inspiration from the United Kingdom’s successful polio wastewater surveillance program. This existing system demonstrated remarkable sensitivity by detecting poliovirus early, enabling rapid public health responses including intensified clinical testing and targeted vaccination drives among vulnerable subgroups. Professor Yoo remarks that such precedents not only validate the technological viability of wastewater surveillance but also underscore its potential as a cornerstone in infectious disease containment strategies, especially when deployed for COVID-19 and other respiratory pathogens.
The mechanics of the warning system hinge on epidemiological thresholds. Specifically, when daily new clinically reported COVID-19 cases surpass 90 cases per million residents in a city housing an LTCF, city authorities would activate a public health alert. This alert recommends administering weekly clinical screening tests among LTCF residents and staff to rapidly identify and isolate infected individuals, curbing transmission chains within facilities known for their susceptibility to outbreaks. The model’s logic rests on the premise that environments like LTCFs demand heightened vigilance given their observed correlation with severe disease outcomes and high mortality.
To substantiate the system’s economic viability, the research team developed complex simulations integrating epidemiological data, health economics, and demographic models tailored to typical LTCF populations in Japan, consisting of roughly 100 residents and 60 staff members. These simulations suggest that the net benefit of deploying wastewater surveillance-enabled warnings at a single LTCF ranges between $5,000 to $49,000 over a critical four-week period of high viral transmission. When these benefits are extrapolated nationally, the aggregated financial gains are staggering, estimated between $3.5 million and $41 million within the same timeframe. These figures highlight the system’s strong potential for cost savings alongside health benefits.
Further amplifying the system’s appeal, social acceptance appears robust. Complementary studies conducted by the research group indicate that the general adult population in Japan exhibits a willingness to allocate approximately $497 million annually in hypothetical budgets supporting WSTPs designed to monitor COVID-19 and other infectious diseases. This social willingness to pay underscores public recognition of wastewater surveillance not merely as a scientific innovation but as a trusted instrument for safeguarding community health.
Wastewater surveillance presents several advantages over traditional clinical surveillance methodologies that rely on collecting individual patient specimens. Foremost, one composite wastewater sample reflects the viral shedding of entire populations, enabling broader epidemiological coverage with fewer resources. Its non-invasive nature accelerates response times, allowing health authorities to detect outbreaks before clinical cases escalate sufficiently to overwhelm hospitals. Moreover, the cost per pathogen tested is significantly reduced by multiplexing in wastewater analysis, where simultaneous detection of multiple viral agents such as influenza and poliovirus is feasible within the same sample.
The researchers emphasize the prospect of scaling the surveillance platform to encompass a wider array of pathogens beyond SARS-CoV-2, facilitated by advancements in molecular assays and metagenomics. For example, incorporating influenza virus into routine wastewater screening could complement seasonal influenza surveillance programs, thereby enriching public health datasets. Japan has already piloted such multi-pathogen surveillance on a limited basis, demonstrating technical feasibility and operational utility. Expansion of this paradigm promises to revolutionize infectious disease monitoring by harnessing wastewater data as a comprehensive population-level diagnostic resource.
As global health systems brace for continually emerging infectious threats, the necessity for scalable, low-cost, and real-time monitoring approaches becomes ever more pressing. Wastewater surveillance embodies these attributes, providing an indispensable adjunct to individual-level testing and contact tracing. The economic and epidemiological insights derived from Professor Yoo and colleagues’ study furnish compelling evidence advocating for policy shifts in Japan and similar contexts worldwide. This research not only advances technical knowledge but also delivers a pragmatic blueprint for integrating environmental surveillance into the fabric of public health infrastructure.
Ultimately, the proposed city-level warning system aspires to transform the management of infectious diseases by embedding wastewater-based epidemiology at the frontline of outbreak detection. By facilitating the swift identification of surges in viral prevalence within communities, this system empowers local governments to implement targeted clinical screening, thereby reducing the severity and scale of COVID-19 waves, especially among vulnerable LTCF populations. This fusion of environmental data with healthcare interventions sets a precedent for holistic infectious disease control strategies in an age increasingly defined by pandemic preparedness.
In conclusion, the economic evaluation of wastewater surveillance-driven warning systems represents a significant scientific contribution, establishing a solid foundation for the broader deployment of such technology in Japan and beyond. As the scientific community continues to embrace interdisciplinary approaches combining environmental sciences, epidemiology, and health economics, the insights gained from this study illuminate new pathways toward sustainable, cost-effective pandemic mitigation strategies. As policymakers grapple with the complexities of balancing public health priorities and economic constraints, tools grounded in wastewater epidemiology offer a promising solution to preempt and control infectious disease outbreaks, safeguarding populations and economies alike.
Subject of Research: People
Article Title: Economic evaluation of the city-level warning system based on surveillance at wastewater treatment plants to recommend optimal clinical COVID-19 screening tests at long-term care facilities, Japan
News Publication Date: 15-Aug-2025
Web References: https://doi.org/10.1016/j.scitotenv.2025.179645
References: Yoo, Byung-Kwang et al. (2025). Economic evaluation of the city-level warning system based on surveillance at wastewater treatment plants to recommend optimal clinical COVID-19 screening tests at long-term care facilities, Japan. Science of The Total Environment, Volume 990.
Image Credits: Byung-Kwang Yoo, Waseda University and Kanagawa University of Human Services
Keywords: Environmental issues, Wastewater, COVID 19, Health care, Medical economics
