Validating Wastewater Surveillance Assays

Developing specific and sensitive molecular assays for detecting pathogens in wastewater was a substantial challenge. Existing clinical assays needed to be evaluated and adapted for the complex and variable wastewater matrix. In addition, many clinical assays were not in the open knowledge domain, limiting understanding of possible cross-reactions in a complex wastewater matrix. Academic and independent research partners, such as the Research Coordination Network members and WastewaterSCAN, a national program based at Stanford and Emory Universities, played a crucial role in this phase by using their speed and research capabilities to develop, pilot, and validate assays. Concurrently, several state and local public health laboratories began developing analytical capabilities and nurturing relationships with wastewater and public health partners to expand wastewater surveillance nationally. Public health partners field-tested those assays by using their applied technical expertise and resources to ensure the assays were accurate and met the necessary standards for public health surveillance and the public health actions associated with detections. The wastewater surveillance Centers of Excellence, launched in August 2022 and led by public health departments and academic partners located in California, Colorado, Texas, New York, North Carolina, and Wisconsin, became learning laboratories for the development and evaluation of assays for new pathogens. Together, those partners established a framework for continuous assay improvement, incorporating feedback from field applications, transparent sharing of available assays, assay validation, and ensuring a nimble response to current infectious disease threats. This approach proved effective during recent outbreaks of monkeypox, influenza A(H5), and measles. Because the Houston Center of Excellence (Houston, TX, USA) developed an assay for measles, they were able to deploy it promptly in Texas and New Mexico. WastewaterSCAN was able to quickly develop, validate, and deploy an assay nationally. CDC used those assays to rapidly implement national surveillance while generating additional validation data and distributing to national testing partners.

Building Relationships with Wastewater Utilities

The involvement of wastewater utilities was essential to the success of wastewater surveillance because wastewater surveillance is not feasible without their routine collection of samples. The Water Environment Federation was a pivotal partner in bridging the gap between the public health and wastewater sectors. Through cross-sector workshops, an annual national wastewater disease surveillance summit, training programs, a community of practice, development of a toolkit to inform health departments collaboration with utilities, podcast episodes and a video series, a utility-focused Web site, and a free autosampler and flow meter initiative, the Water Environment Federation enabled introductions across disciplines and lowered barriers to entry for utilities joining wastewater surveillance efforts. The collaboration enhanced the quality of data collected and promoted a shared understanding of the necessity of wastewater surveillance in public health.

Data Systems for Bidirectional Communication

A robust data infrastructure was necessary to enable bidirectional communication between CDC and STLT health departments, on the basis of the foundational concept that the “basis of effective surveillance is the current and accurate 2-way flow of information among all those who need to know” (1). Before the COVID-19 pandemic, public health surveillance platforms were not designed for wastewater data, which includes metadata on the sample, spatial sewershed data, and the ability to collect, analyze, and provision the data in real time to frontline health departments. Wastewater surveillance was established on a platform that enabled real-time data sharing between CDC and STLT partners, had the ability to rapidly set up data pipelines for new pathogen targets, and was in alignment with CDC’s Data Modernization Initiative (2). National public health partners provided guidance on data standardization and interoperability and convened key state and territorial stakeholders to ensure data were available for public health response. The development of plain-language data dashboards enabled the public and public health jurisdictions to visualize trends, make data meaningful for public audiences, and respond promptly to emerging public health threats. This system exemplified the principles of public health surveillance by promoting timely data sharing and actionable insights and communicating findings for public health action (3,4).

Increasing Capacity, Knowledge, and Training for a Wastewater Surveillance Workforce

A critical component of wastewater surveillance for infectious diseases is the public health capacity to test and analyze data and interpret results in a way that informs public health action. Funding was provided directly to state, territorial, local, and tribal health departments to establish their wastewater testing laboratories and surveillance programs. Public health partners provided input to guide capacity building by mentoring, developing standards, and addressing public health ethics (5). Academic and clinical partners, including those associated with the wastewater surveillance Centers of Excellence, equipped public health professionals with the necessary skills in data interpretation, laboratory techniques, and community and clinician engagement strategies. Communities of practice developed by partner organizations were instrumental in helping the new utility, laboratory and health department workforce connect and share successes and challenges. The Association of Public Health Laboratories (APHL) Wastewater Surveillance Laboratory Community of Practice started in 2020 as a small group of laboratories who met monthly to discuss the challenges of onboarding this testing; it has grown to include 643 members. Monthly presentation- and discussion-based calls cover all aspects of laboratory implementation of wastewater surveillance, including new targets for testing, workflow efficiencies, and sequencing. Other workforce development efforts include APHL and Council of State and Territorial Epidemiologists peer-to-peer network programs that provided bidirectional in-person visits between jurisdictions to learn new techniques and establish collaborative relationships. Those development efforts include APHL fellowship and internship programs that have sponsored 432 fellows and 298 interns in state and local public health laboratories.

Throughout the United States, local and state health departments are working in collaboration with utilities, academic institutions, and private partners to advance wastewater surveillance. Local health departments (LHDs) play a critical role in those efforts by using wastewater data to inform public health action. Although some LHDs lead wastewater surveillance activities and manage testing directly, others play a more supportive or coordination-based role; however, all contribute critically to developing a comprehensive wastewater surveillance system.

To strengthen local capacity, the National Association of County and City Health Officials (NACCHO), with support from CDC, launched the Wastewater Surveillance Mentorship Program. NACCHO identifies LHDs that have extensive wastewater surveillance experience (mentors) and pairs them with LHDs in the early stages of program development (mentees). Throughout the program, mentors provide tailored technical assistance to help mentees design, implement, and strengthen their wastewater surveillance programs on the basis of their specific goals and jurisdictional needs.

To further expand support and create wider access to wastewater surveillance expertise, NACCHO launched the Fostering Local Wastewater Monitoring Network, a community of practice designed for LHD staff at all experience levels. By investing in workforce capacity in frontline public health, health departments can effectively use wastewater data to inform public health decisions and align with the principles of public health surveillance that continually adapt to evolving health challenges (6,7).

Developing the Science Base, Innovation, and Ethical Framework

To meet emerging and reemerging infectious disease threats, wastewater surveillance requires continual innovation. Although it began as an innovative system to provide critical data on community levels of COVID-19, wastewater surveillance has expanded to numerous pathogens on the basis of the public health need, most recently including influenza, monkeypox, and measles virus. Innovation requires continued engagement with academic partners such as WastewaterSCAN and the Centers of Excellence to expand the science base.

The collective expertise of academic partners, public health organizations, and wastewater utilities fosters an environment that is conducive to experimentation and adaptation but also promotes ethical public health practice. The Association of State and Territorial Health Officials engaged with CDC and the Centers of Excellence to develop an applied ethical framework (5). This framework offers guidance to utility partners, health departments, academic partners, and policymakers involved in protecting privacy, preventing stigma, ensuring proper data stewardship, and helping build trust with contributing communities and clinical professionals to enable the effective use of wastewater data for infectious disease surveillance (8,9). A strong focus on partnerships enabled the US wastewater surveillance program to embrace new technologies and methodologies and demonstrate leadership in public health innovation, which is a key marker of successful public health innovation (6,7).

Supporting Public Health Action

The core purpose of public health surveillance is effective and timely public health action. Public health partners provided key support to ensure that wastewater signals informed public health action for each new pathogen target. They developed response checklists, public communication strategies, and data visualizations that enabled health departments to use wastewater data for the early detection of outbreaks, monitoring persistent infectious disease threats, assessing public health interventions, and providing data that the public can use to inform and protect themselves. Partners provided ongoing feedback and input to develop and continually refine those public health action tools.