Benefits of Wastewater Surveillance for Combating Infectious Diseases

A recently released report from an expert committee of the National Academies of Sciences, Engineering, and Medicine — including Stanford Law School and Department of Health Policy professor Michelle Mello and former Rosenkranz Prize winner Ami Bhatt — focuses on how wastewater monitoring has become a critical tool in the fight against infectious diseases.
Wastewater plant

“I never thought I’d say this, but it’s an exciting time to be talking about sewage,” said Michelle Mello (BA ’93), Stanford Law School professor and professor of health policy at the Stanford University School of Medicine. A member of the National Academies of Sciences, Engineering, and Medicine’s Committee on Community Wastewater-based Infectious Disease Surveillance, Mello is the co-author of Wastewater-based Disease Surveillance for Public Health Action, a report released January 19. Stanford Medicine professor Ami Bhatt — a Stanford Health Policy Rosenkranz Prize winner — worked with Mello and the other committee members on the report.

The peer-reviewed report, produced at the request of the Centers for Disease Control and Prevention (CDC), details how community-level wastewater surveillance has been critical for informing public health decisions during the COVID-19 pandemic, such as when to lift mask mandates and where to situate testing and vaccination sites. The report offers recommendations to strengthen nationwide coordination and ensure a national wastewater surveillance system that is flexible, equitable, and sustainable to inform the public health response to COVID-19 and future infectious diseases.   

“The pandemic spurred tremendous innovation and technological advances in wastewater surveillance,” Mello said. “The challenge now is how to sustain and build on that to make this success story permanent. Too often, we quickly shift our attention and resources to other problems once a disease outbreak or epidemic starts quieting down, instead of reflecting on what needs to be in place to combat the next outbreak. Now is exactly the right moment to do that work so we’re better prepared next time.”


NASEM graphic on wastewater surveillance report

According to the report, the needed work includes refining and standardizing methods of wastewater surveillance, developing criteria and processes for deciding which pathogens to monitor, and ensuring that all localities have the resources and information they need to participate in a truly representative national system. “An important focus of the report is a discussion of building public trust in the system,” Mello said, “including communicating how wastewater surveillance benefits our communities while addressing privacy concerns.” 

About 84 percent of U.S. households are connected to municipal wastewater collection systems, according to the CDC. Wastewater-based infectious disease surveillance systems detect the presence of biomarkers of pathogens, such as microbial DNA or RNA, that are shed into a municipal sewer system. During the pandemic, wastewater surveillance provided early indications of changes in community levels of SARS-CoV-2, as well as emerging variants of the virus, sometimes weeks ahead of other public health data. As more people shifted from PCR testing for COVID-19 at medical facilities and mass testing sites to antigen testing at home, wastewater analysis also helped compensate for the resulting bias in reporting positive results to public health departments. 

The report also discusses the importance of a monitoring system that is fiscally and operationally sustainable and monitors populations equitably. When evaluating potential targets for future wastewater surveillance, the report says, CDC should establish a transparent process for prioritizing pathogens, and consider three criteria: the public health significance of the threat, the analytical feasibility for wastewater surveillance, and the usefulness of community-level data to inform public health action.

The National Academies of Sciences, Engineering, and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice to the U.S. to solve complex problems and inform public policy decisions related to science, technology, and medicine. For each requested study, panel members are chosen for their expertise and experience and serve pro bono to carry out the study’s statement of task.

Monica Schreiber is the Assistant Director of Communications at the Stanford School of Law.