Smaller cities and rural towns are finding the NWSS a useful early warning tool for tracking COVID-19 in their communities
In a move that mirrors similar programs around the world, the federal Centers for Disease Control and Prevention (CDC) now monitors sewage nationwide and records levels of SARS-CoV-2 in an effort to prevent new outbreaks of COVID-19 and spot any new variants of the coronavirus.
Advances in gene sequencing technologies are enabling the CDC’s National Wastewater Surveillance System (NWSS), and in many communities, clinical laboratories and health system laboratories have worked with local health authorities to test wastewater since onset of the pandemic.
Dark Daily first covered the CDC’s intention to develop the NWSS in a 2020 ebriefing, titled, “CDC, HHS Create National Wastewater Surveillance System to Help Monitor and Track Spread of COVID-19.” The CDC detailed its latest progress implementing the NWSS in a recent media telebriefing.
“What started as a grassroots effort by academic researchers and wastewater utilities has quickly become a nationwide surveillance system with more than 34,000 samples collected representing approximately 53 million Americans,” noted epidemiologist Amy Kirby, PhD (above) during the telebriefing.
Kirby is a Senior Service Fellow in the Waterborne Disease Prevention Branch at the CDC.
“Currently, CDC is supporting 37 states, four cities, and two territories to help develop wastewater surveillance systems in their communities. More than 400 testing sites around the country have already begun their wastewater surveillance efforts,” she added.
Genetic Sequencing Enables Tracking of Virus and Bacteria
At the time of the telebriefing, the federal agency anticipated having an additional 250 sites online within a few weeks and even more sites added within the coming months. Many of the participating sites are sequencing the genes of their biological samples and reporting that data to the CDC.
“So, we’ve seen from very early days in the pandemic that rates of detection in wastewater correlate very well with other clinical indicators, like pace rates and hospitalization and test positivity,” Kirby stated. “That data continues to come in and it continues to be a very solid indicator of what’s going on in the community.”
Wastewater, also referred to as sewage, includes water from toilets, showers, and sinks that may contain human fecal matter and water from rain and industrial sources. To use the CDC’s wastewater surveillance system:
- Wastewater is collected from a community area served by the surveillance system as it flows into a local water treatment plant.
- Collected samples are sent to an environmental or public health laboratory where they are tested for SARS-CoV-2.
- Health departments submit the testing data to the CDC through the online NWSS Data Collection and Integration for Public Health Event Response (DCIPHER) portal.
- The DCIPHER system then analyzes the data and reports the results back to the health department for use in their COVID-19 response.
Beginning in February 2022, members of the public can view the results of collected data online through the CDC’s COVID Data Tracker.
Wastewater Sampling Is a ‘Critical Early Warning System’
According to the CDC NWSS website, there are many advantages to using wastewater surveillance in the fight against COVID-19, including:
- Wastewater can capture the presence of the virus shed by people both with and without symptoms.
- Health officials can determine if infections are increasing or decreasing within a certain monitoring site.
- Wastewater surveillance does not depend on people having access to healthcare or the availability of COVID-19 testing.
- It is possible to implement wastewater surveillance in many communities as nearly 80% of the US population are served by municipal wastewater collection systems.
“These built-in advantages can inform important public health decisions, such as where to allocate mobile testing and vaccination sites,” Kirby said. “Public health agencies have also used wastewater data to forecast changes in hospital utilization, providing additional time to mobilize resources and preparation for increasing cases.”
The wastewater sampling represents a critical early warning system for COVID-19 surges and variants, and the CDC hopes this type of sampling and research can be utilized in the future for other infectious diseases.
“Wastewater surveillance can be applicable to a wide variety of health concerns. And so, we are working to expand the National Wastewater Surveillance platform to use it for gathering data on other pathogens, and we expect that work to commence by the end of this year,” Kirby said. “Our targets include antibiotic resistance, foodborne infections like E. Coli, salmonella, norovirus, influenza, and the emerging fungal pathogen Candida Auris.”
Critical Surveillance Tool for Microbiology Laboratories
Independent of the nation’s network of public health laboratories, expansion of this program may give microbiology and clinical laboratories in smaller cities and rural towns an opportunity to test wastewater specimens in support of local wastewater monitoring programs.
As the CDC develops this surveillance network into a more formal program, microbiology labs may find it useful to learn which infectious diseases are showing up in their localities, often days or weeks before any patients test positive for the same infectious agents.
That would give pathologists and clinical laboratory leaders an early warning to be on the alert for positive test results of infectious diseases that wastewater monitoring has confirmed exist in the community.