Post by Nadica (She/Her) on Jul 25, 2024 2:48:41 GMT
Wastewater surveillance for Covid-19 keeps evolving. Here’s what you need to know. - Published July 23, 2024
Key points you should know:
Wastewater surveillance is a key remaining metric for tracking Covid-19 spread. There are several national, state, and local dashboards where you can find data.
Biobot Analytics recently ended its popular dashboard due to a lack of internal resources, but continues to provide weekly updates.
WastewaterSCAN recently cut back its testing sites, including many sites in California, but continues testing for SARS-CoV-2 and 10 other pathogens.
The CDC’s wastewater dashboard, while the most comprehensive source of these data, may present Covid-19 levels as “low” when the virus is still spreading widely.
Wastewater data are an imperfect proxy for cases and can’t be directly translated into numbers of sick people; scientists still have a lot to learn about this.
Long-term funding is needed from federal and state governments to support more sustainable surveillance programs.
As governments have scaled back their tracking of Covid-19 — even while the pandemic continues — many people who still take precautions have increasingly relied on wastewater surveillance to follow disease trends. But wastewater data can be confusing and inconsistent, especially as surveillance programs change over time.
Early in the pandemic, scientists realized that they could track Covid-19 through our sewers by testing waste samples for SARS-CoV-2. Many scientific studies have since found that viral levels in our waste rise and fall in tandem with Covid-19 cases in the community. And, since thousands of people contribute waste to the same sewershed, wastewater surveillance offers population-level data, including people who don’t get tested or seek healthcare.
This approach comes with downsides, though. Scientists who work on wastewater monitoring programs don’t know exactly how many people are included in a given sample, or how environmental factors like weather and animal populations may interfere with their analysis. We also don’t know how the coronavirus’ continued evolution has impacted the ways people “shed” virus (as the scientists put it) in their waste.
As a journalist who has focused on Covid-19 surveillance since early in the pandemic, I have closely followed this evolving field. In this article, I explain a couple of recent changes to the wastewater testing landscape, share where to find data right now, and answer readers’ questions.
Where to find wastewater data right now
As I wrote for Scientific American last winter, wastewater experts recommend looking for wastewater testing sites “closest to where you live” for the data that will be most relevant to your community. You can find these sites in a few places:
The Centers for Disease Control and Prevention (CDC)’s National Wastewater Surveillance System (NWSS): The CDC’s wastewater program compiles data from state and local health departments and from some sites that are tested through a CDC contract with a private company. It includes about 1,200 testing sites in total. You can find individual testing site data on this map, and find national, regional, and state trends here.
WastewaterSCAN: This program, based at Stanford University, started in 2020 by testing for SARS-CoV-2 in the Bay Area, then expanded to more locations and more pathogens. It currently includes 148 testing sites across 40 states (following a recent decrease in site numbers), and offers data for individual sites as well as national and regional trends.
Biobot Analytics: This startup company has its own network of coronavirus testing sites and was previously a testing contractor for the CDC. This past May, Biobot discontinued its popular Covid-19 dashboard, but the company still provides regular data updates through “Respiratory Risk Reports.”
State and local dashboards: Some state and local public health departments offer their own wastewater surveillance dashboards. You can find a list here. These dashboards are more tailored to their local communities than the national pages, and may be updated more frequently.
COVIDPoops19: This global repository, maintained by Colleen Naughton and her colleagues at the University of California Merced, links out to about 200 dashboard representing over 4,600 testing sites in 72 countries. It’s another great place to find data near you.
In May, Biobot Analytics caused a stir in the Long Covid and Covid-cautious communities when the company took down its popular dashboard, which had previously been the longest-running source for Covid-19 wastewater data in the U.S. Biobot continues to share data through weekly reports, but these updates are less comprehensive than the dashboard, which had included historical and county-level data for sites in Biobot’s network.
Biobot ended its dashboard for two reasons, said Mariana Matus, the company’s CEO, in an interview with The Sick Times. First, “we felt that the CDC dashboard had evolved enough to provide a similar level of information” to Biobot’s, she said, referring to the national, regional, and state-level trends that the CDC dashboard began publishing last winter. Second, last year, Biobot lost a contract with the CDC, which made it necessary for the company to reduce costs, Matus said.
“We understand that it’s not ideal,” Matus said. “Unfortunately, we just don’t have the resources.” She compared the move to John Hopkins University and the COVID Tracking Project (where this writer was a volunteer back in 2020) ending their data collection efforts earlier in the pandemic and similarly directing people to CDC resources. This surveillance work is ultimately a job for government agencies, Matus said.
Following the dashboard’s end, Biobot continues to share national and regional Covid-19 updates, along with flu and RSV data, in its weekly Respiratory Risk Reports. These reports include trends from about 150 to 200 testing sites that remain in Biobot’s network, Matus said. Epidemiologists at the company compile the reports during respiratory virus season (September through April) and other periods of high viral activity, such as the current summer Covid-19 wave.
Meanwhile, WastewaterSCAN recently cut the number of sites in its surveillance program: as of early July, the organization went from 194 to 148 sites, representing a 24% decrease. “WastewaterSCAN entered a new phase of its wastewater monitoring program,” the WastewaterSCAN team said in a statement to The Sick Times. This new phase will focus on other, more “disruptive” projects, Alexandria Boehm, one of the program’s principal scientists and a civil and environmental engineer at Stanford, told STAT News. STAT also reported that “resource constraints” contributed to the site change.
The WastewaterSCAN team “worked closely” with wastewater monitoring plants and public health officials to identify which sites to cut from its network, they said. The remaining 148 sites serve a total of 39 million people across 40 states, and the team does not anticipate significant changes to the reliability of WastewaterSCAN’s calculations of low, medium, and high levels for different pathogens, according to their statement. Data downloads also continue to be available from WastewaterSCAN, now from the Stanford Digital Repository site.
Of the 46 sites no longer participating in this program, 31 were located in California — representing a significant cut to wastewater monitoring in the state. As WastewaterSCAN is based at Stanford, the program has included many California sites (59 prior to July). In response to a question about this change, WastewaterSCAN said they continue to “work closely” with treatment plants across California, and directed readers to a dashboard published by the California state health department.
While plenty of testing continues, these changes from Biobot Analytics and WastewaterSCAN emphasize a challenge I’ve covered before: wastewater surveillance programs need long-term funding. In my reporting, scientists across the U.S. and internationally have told me that these programs ultimately should be integrated into public health departments and should have permanent budgets — it shouldn’t be up to private companies and academic researchers to run these vital surveillance systems.
How to understand the CDC’s dashboard
The CDC’s wastewater dashboard is our most comprehensive data source but its trends should be viewed with caution. The agency’s NWSS program has a unique challenge: presenting data from different public health agencies and testing companies in a unified format. As wastewater surveillance methods are not standardized, it’s not possible to directly compare data from different testing programs.
CDC scientists addressed this challenge by developing a new metric called the Wastewater Viral Activity Level, introduced last winter. For every testing site, the CDC calculates a “baseline” level of SARS-CoV-2 spread based on historical data. Then, every new measurement that comes in is compared to the site’s baseline and assigned an “Activity Level” value — higher for further above the baseline, lower for closer to the baseline. The CDC then aggregates these “Activity Levels” by taking the middle, or median, values across all sites in a state, then across all states to yield the state, regional, and national-level numbers reported on the dashboard.
“This metric accounts for variations in wastewater system design and operation, size of the population represented by a wastewater sample, and laboratory testing methods,” Dr. Amy Kirby, team lead for NWSS, said in a statement to The Sick Times. The Wastewater Viral Activity Level “is intended to show broad changes over time and is most appropriate for state, regional, and national overviews.” Sites must have at least six weeks of data available to calculate their baseline, Kirby said, and the CDC recalculates these baselines every six months, on January 1 and July 1.
The recalculation process can lead to interruptions in public data presentation, said Patrick Vaughan, an engineer who closely follows wastewater data on his TikTok and YouTube accounts. In the CDC’s first weekly update of July, for example, the national Wastewater Viral Activity Level suddenly jumped from “low” to “high” because the NWSS team had just re-adjusted site baselines, he said.
These CDC baselines also are set at higher levels than many people in the Covid-conscious community would consider to actually be “low community risk for Covid-19,” because they use recent months of data — during the Omicron era of the pandemic in which levels never really go down. “When you have high high data for long periods of time, [the CDC dashboard is] going to make it seem like it’s low levels, because you’re not that many standard deviations from that baseline,” Vaughan said.
Because of this baseline process, the CDC dashboard may sometimes present Wastewater Viral Activity Levels for certain states, regions, or the U.S. as a whole as lower than other dashboards that are more localized. For example, in late June, a Weather Report from the People’s CDC observed that WastewaterSCAN reported “high” levels nationally while the CDC reported “low” levels.
“Right now, we’re in the highest summer wave of the entirety of the pandemic,” at least according to wastewater data, Vaughan said. These high wastewater values have been clear since mid-June, but the CDC was reporting low levels until July, he said: anyone using those CDC levels as a basis for their preventative measures was a month late on recognizing this summer’s wave. The CDC has also received criticism for presenting wastewater levels in an all-blue color scheme that looks “calming” even during surges.
When asked about differences between the CDC and other dashboards, Kirby said the six-month baseline calculation is “unique to the CDC.” She also referenced differences in the number and geographic distribution of testing sites between the CDC and other data sources.
Interpreting wastewater data
Here are a few responses to readers’ questions that weren’t already answered in the prior sections.
How do you interpret wastewater data? Is this information reliable?
Quoting from my Scientific American story published last December:
To understand wastewater trends, ask yourself two questions: First, what are the current levels of SARS-CoV-2 in your community’s sewage? For example, WastewaterSCAN’s dashboard labels testing site results as “high,” “medium” or “low” based on how their current viral levels, compare with measurements accumulated over the past year… Second, are the trends during the recent weeks going up or down or staying stable? Such changes should match increasing or decreasing COVID spread in the community.
As you consider these factors, remember that wastewater data are not directly representative of sick people in a community. It’s better to think of these numbers as a proxy for case numbers — if levels are high, you can be pretty confident that a lot of people are sick, but you can’t pinpoint exactly how many.
Remember also that scientists must make a lot of decisions behind the scenes to analyze their sewage test results and present them publicly. The CDC’s dashboard is one prominent example, but all dashboards have some element of this decision-making, usually explained in their methodology sections. For instance, Vaughan has examined the WastewaterSCAN site and found that the team does multiple rounds of averaging for new wastewater measurements, which removes higher values from the data.
Local wastewater data also tend to be more reliable over time, compared to regional and national data. If you follow a testing site in your city or county, those data will consistently represent the same population over time. You won’t have to worry about the averages-of-averages that happen when scientists calculate trends for larger geographic regions.
Can we “translate” wastewater data into case numbers?
Not directly. This explainer that I wrote for The Sick Times in February discusses this challenge, as does my story for Nature from this spring. We don’t know enough about how different people “shed” coronavirus in their waste, or about how the virus’ evolution has impacted this process, to do this “translation” reliably. I personally will sometimes look at forecasts like those by Mike Hoerger and JP Weiland, but I take them as a suggestion of potential case counts, not an accurate representation.
As I wrote in February: “True infection rates could be lower than wastewater data make them appear, or they could be higher. This is why I typically reference other sources in addition to wastewater data, rather than relying on just one type of tracking.” For similar reasons, a couple of different modeling groups have found that using wastewater data in tandem with other data sources, such as hospitalizations, tends to lead to more accurate predictions than using one metric on its own.
What do I do if there are no testing sites in my community?
I put this question to a few experts when working on this story, and Colleen Naughton (who runs the COVIDPoops19 dashboard) had a great response:
My recommendation would be to try to look at nearby sites since their site may experience similar trends. For example, if there is an increase in a site that is a major urban center near you then it may also be increasing your area, especially if people commute to that area. The state viral activity levels for the CDC NWSS can still be a good reflection of how the virus may be in that state compared to past trends. Also, if neighboring states are increasing that may be a sign that it could increase in your state soon.
What is the relationship between WastewaterSCAN, Verily, and the CDC?
Verily, a health tech company owned by Alphabet (Google’s parent company), helps to collect and test wastewater samples for both WastewaterSCAN and the CDC. Verily has worked with WastewaterSCAN for a couple of years, and became a contractor for CDC NWSS (replacing Biobot) last fall. The company also helps share data from WastewaterSCAN sites with the CDC.
In other words, the sites in WastewaterSCAN and the sites that Verily tests for its CDC contract are two separate groups of wastewater treatment plants. WastewaterSCAN sites are included in the CDC dashboard, but not the other way around.
What is the current funding situation for these programs?
The CDC NWSS team is working on expanding wastewater surveillance across the U.S., Kirby said in her statement to The Sick Times. CDC scientists are supporting state, local, and tribal health departments, while also working to develop standards (and the National Institute of Standards and Technology is working on standards, too).
However, the CDC and other health agencies need more funding to expand current testing programs and support them long-term. As I reported last year, CDC NWSS currently has funding through 2025, and will need more support after that. This piece at the COVID-19 Data Dispatch has more details about the funding landscape; note that it was written before the CDC changed contractors from Biobot to Verily.
When I asked for updates about CDC funding, Kirby shared: “The FY 2025 President’s Budget request includes $20 million in new base funding that will allow CDC to support a limited number of states for wastewater surveillance to continue public health laboratory capabilities and wastewater programs and allow innovation for detecting other infectious disease threats once supplemental funds are depleted.” Congress may also add wastewater surveillance support when it reauthorizes the Pandemic and All-Hazards Preparedness Act, a federal bill that expired recently; last year, three Senators introduced a wastewater provision to this Act.
What actions can we take to support more wastewater testing?
Readers interested in seeing continued wastewater testing can consider:
Ask your representatives in Congress to support CDC NWSS in the FY 2025 budget and through reauthorizing the Pandemic and All-Hazards Preparedness Act.
Encourage your state and local governments to fund wastewater testing at these levels. New York State offers one notable example: Governor Kathy Hochul included an expansion of wastewater surveillance in the state’s 2023 budget.
Ask your local wastewater treatment plants to get involved with testing. Public health officials or companies have to work with these plants to collect samples, which is often a “limiting factor” in expanding testing, Matus, from Biobot, said. Community members can reach out to these plants directly and let them know there is interest in testing, she said.
If you live in or have connections to Canada, consider signing this petition encouraging continued wastewater surveillance in Ontario. “We believe canceling this program is dangerous, short-sighted, and anti-science,” said a member of the volunteer group behind this petition in an email to The Sick Times.
All articles by The Sick Times are available for other outlets to republish free of charge. We request that you credit us and link back to our website.
Key points you should know:
Wastewater surveillance is a key remaining metric for tracking Covid-19 spread. There are several national, state, and local dashboards where you can find data.
Biobot Analytics recently ended its popular dashboard due to a lack of internal resources, but continues to provide weekly updates.
WastewaterSCAN recently cut back its testing sites, including many sites in California, but continues testing for SARS-CoV-2 and 10 other pathogens.
The CDC’s wastewater dashboard, while the most comprehensive source of these data, may present Covid-19 levels as “low” when the virus is still spreading widely.
Wastewater data are an imperfect proxy for cases and can’t be directly translated into numbers of sick people; scientists still have a lot to learn about this.
Long-term funding is needed from federal and state governments to support more sustainable surveillance programs.
As governments have scaled back their tracking of Covid-19 — even while the pandemic continues — many people who still take precautions have increasingly relied on wastewater surveillance to follow disease trends. But wastewater data can be confusing and inconsistent, especially as surveillance programs change over time.
Early in the pandemic, scientists realized that they could track Covid-19 through our sewers by testing waste samples for SARS-CoV-2. Many scientific studies have since found that viral levels in our waste rise and fall in tandem with Covid-19 cases in the community. And, since thousands of people contribute waste to the same sewershed, wastewater surveillance offers population-level data, including people who don’t get tested or seek healthcare.
This approach comes with downsides, though. Scientists who work on wastewater monitoring programs don’t know exactly how many people are included in a given sample, or how environmental factors like weather and animal populations may interfere with their analysis. We also don’t know how the coronavirus’ continued evolution has impacted the ways people “shed” virus (as the scientists put it) in their waste.
As a journalist who has focused on Covid-19 surveillance since early in the pandemic, I have closely followed this evolving field. In this article, I explain a couple of recent changes to the wastewater testing landscape, share where to find data right now, and answer readers’ questions.
Where to find wastewater data right now
As I wrote for Scientific American last winter, wastewater experts recommend looking for wastewater testing sites “closest to where you live” for the data that will be most relevant to your community. You can find these sites in a few places:
The Centers for Disease Control and Prevention (CDC)’s National Wastewater Surveillance System (NWSS): The CDC’s wastewater program compiles data from state and local health departments and from some sites that are tested through a CDC contract with a private company. It includes about 1,200 testing sites in total. You can find individual testing site data on this map, and find national, regional, and state trends here.
WastewaterSCAN: This program, based at Stanford University, started in 2020 by testing for SARS-CoV-2 in the Bay Area, then expanded to more locations and more pathogens. It currently includes 148 testing sites across 40 states (following a recent decrease in site numbers), and offers data for individual sites as well as national and regional trends.
Biobot Analytics: This startup company has its own network of coronavirus testing sites and was previously a testing contractor for the CDC. This past May, Biobot discontinued its popular Covid-19 dashboard, but the company still provides regular data updates through “Respiratory Risk Reports.”
State and local dashboards: Some state and local public health departments offer their own wastewater surveillance dashboards. You can find a list here. These dashboards are more tailored to their local communities than the national pages, and may be updated more frequently.
COVIDPoops19: This global repository, maintained by Colleen Naughton and her colleagues at the University of California Merced, links out to about 200 dashboard representing over 4,600 testing sites in 72 countries. It’s another great place to find data near you.
In May, Biobot Analytics caused a stir in the Long Covid and Covid-cautious communities when the company took down its popular dashboard, which had previously been the longest-running source for Covid-19 wastewater data in the U.S. Biobot continues to share data through weekly reports, but these updates are less comprehensive than the dashboard, which had included historical and county-level data for sites in Biobot’s network.
Biobot ended its dashboard for two reasons, said Mariana Matus, the company’s CEO, in an interview with The Sick Times. First, “we felt that the CDC dashboard had evolved enough to provide a similar level of information” to Biobot’s, she said, referring to the national, regional, and state-level trends that the CDC dashboard began publishing last winter. Second, last year, Biobot lost a contract with the CDC, which made it necessary for the company to reduce costs, Matus said.
“We understand that it’s not ideal,” Matus said. “Unfortunately, we just don’t have the resources.” She compared the move to John Hopkins University and the COVID Tracking Project (where this writer was a volunteer back in 2020) ending their data collection efforts earlier in the pandemic and similarly directing people to CDC resources. This surveillance work is ultimately a job for government agencies, Matus said.
Following the dashboard’s end, Biobot continues to share national and regional Covid-19 updates, along with flu and RSV data, in its weekly Respiratory Risk Reports. These reports include trends from about 150 to 200 testing sites that remain in Biobot’s network, Matus said. Epidemiologists at the company compile the reports during respiratory virus season (September through April) and other periods of high viral activity, such as the current summer Covid-19 wave.
Meanwhile, WastewaterSCAN recently cut the number of sites in its surveillance program: as of early July, the organization went from 194 to 148 sites, representing a 24% decrease. “WastewaterSCAN entered a new phase of its wastewater monitoring program,” the WastewaterSCAN team said in a statement to The Sick Times. This new phase will focus on other, more “disruptive” projects, Alexandria Boehm, one of the program’s principal scientists and a civil and environmental engineer at Stanford, told STAT News. STAT also reported that “resource constraints” contributed to the site change.
The WastewaterSCAN team “worked closely” with wastewater monitoring plants and public health officials to identify which sites to cut from its network, they said. The remaining 148 sites serve a total of 39 million people across 40 states, and the team does not anticipate significant changes to the reliability of WastewaterSCAN’s calculations of low, medium, and high levels for different pathogens, according to their statement. Data downloads also continue to be available from WastewaterSCAN, now from the Stanford Digital Repository site.
Of the 46 sites no longer participating in this program, 31 were located in California — representing a significant cut to wastewater monitoring in the state. As WastewaterSCAN is based at Stanford, the program has included many California sites (59 prior to July). In response to a question about this change, WastewaterSCAN said they continue to “work closely” with treatment plants across California, and directed readers to a dashboard published by the California state health department.
While plenty of testing continues, these changes from Biobot Analytics and WastewaterSCAN emphasize a challenge I’ve covered before: wastewater surveillance programs need long-term funding. In my reporting, scientists across the U.S. and internationally have told me that these programs ultimately should be integrated into public health departments and should have permanent budgets — it shouldn’t be up to private companies and academic researchers to run these vital surveillance systems.
How to understand the CDC’s dashboard
The CDC’s wastewater dashboard is our most comprehensive data source but its trends should be viewed with caution. The agency’s NWSS program has a unique challenge: presenting data from different public health agencies and testing companies in a unified format. As wastewater surveillance methods are not standardized, it’s not possible to directly compare data from different testing programs.
CDC scientists addressed this challenge by developing a new metric called the Wastewater Viral Activity Level, introduced last winter. For every testing site, the CDC calculates a “baseline” level of SARS-CoV-2 spread based on historical data. Then, every new measurement that comes in is compared to the site’s baseline and assigned an “Activity Level” value — higher for further above the baseline, lower for closer to the baseline. The CDC then aggregates these “Activity Levels” by taking the middle, or median, values across all sites in a state, then across all states to yield the state, regional, and national-level numbers reported on the dashboard.
“This metric accounts for variations in wastewater system design and operation, size of the population represented by a wastewater sample, and laboratory testing methods,” Dr. Amy Kirby, team lead for NWSS, said in a statement to The Sick Times. The Wastewater Viral Activity Level “is intended to show broad changes over time and is most appropriate for state, regional, and national overviews.” Sites must have at least six weeks of data available to calculate their baseline, Kirby said, and the CDC recalculates these baselines every six months, on January 1 and July 1.
The recalculation process can lead to interruptions in public data presentation, said Patrick Vaughan, an engineer who closely follows wastewater data on his TikTok and YouTube accounts. In the CDC’s first weekly update of July, for example, the national Wastewater Viral Activity Level suddenly jumped from “low” to “high” because the NWSS team had just re-adjusted site baselines, he said.
These CDC baselines also are set at higher levels than many people in the Covid-conscious community would consider to actually be “low community risk for Covid-19,” because they use recent months of data — during the Omicron era of the pandemic in which levels never really go down. “When you have high high data for long periods of time, [the CDC dashboard is] going to make it seem like it’s low levels, because you’re not that many standard deviations from that baseline,” Vaughan said.
Because of this baseline process, the CDC dashboard may sometimes present Wastewater Viral Activity Levels for certain states, regions, or the U.S. as a whole as lower than other dashboards that are more localized. For example, in late June, a Weather Report from the People’s CDC observed that WastewaterSCAN reported “high” levels nationally while the CDC reported “low” levels.
“Right now, we’re in the highest summer wave of the entirety of the pandemic,” at least according to wastewater data, Vaughan said. These high wastewater values have been clear since mid-June, but the CDC was reporting low levels until July, he said: anyone using those CDC levels as a basis for their preventative measures was a month late on recognizing this summer’s wave. The CDC has also received criticism for presenting wastewater levels in an all-blue color scheme that looks “calming” even during surges.
When asked about differences between the CDC and other dashboards, Kirby said the six-month baseline calculation is “unique to the CDC.” She also referenced differences in the number and geographic distribution of testing sites between the CDC and other data sources.
Interpreting wastewater data
Here are a few responses to readers’ questions that weren’t already answered in the prior sections.
How do you interpret wastewater data? Is this information reliable?
Quoting from my Scientific American story published last December:
To understand wastewater trends, ask yourself two questions: First, what are the current levels of SARS-CoV-2 in your community’s sewage? For example, WastewaterSCAN’s dashboard labels testing site results as “high,” “medium” or “low” based on how their current viral levels, compare with measurements accumulated over the past year… Second, are the trends during the recent weeks going up or down or staying stable? Such changes should match increasing or decreasing COVID spread in the community.
As you consider these factors, remember that wastewater data are not directly representative of sick people in a community. It’s better to think of these numbers as a proxy for case numbers — if levels are high, you can be pretty confident that a lot of people are sick, but you can’t pinpoint exactly how many.
Remember also that scientists must make a lot of decisions behind the scenes to analyze their sewage test results and present them publicly. The CDC’s dashboard is one prominent example, but all dashboards have some element of this decision-making, usually explained in their methodology sections. For instance, Vaughan has examined the WastewaterSCAN site and found that the team does multiple rounds of averaging for new wastewater measurements, which removes higher values from the data.
Local wastewater data also tend to be more reliable over time, compared to regional and national data. If you follow a testing site in your city or county, those data will consistently represent the same population over time. You won’t have to worry about the averages-of-averages that happen when scientists calculate trends for larger geographic regions.
Can we “translate” wastewater data into case numbers?
Not directly. This explainer that I wrote for The Sick Times in February discusses this challenge, as does my story for Nature from this spring. We don’t know enough about how different people “shed” coronavirus in their waste, or about how the virus’ evolution has impacted this process, to do this “translation” reliably. I personally will sometimes look at forecasts like those by Mike Hoerger and JP Weiland, but I take them as a suggestion of potential case counts, not an accurate representation.
As I wrote in February: “True infection rates could be lower than wastewater data make them appear, or they could be higher. This is why I typically reference other sources in addition to wastewater data, rather than relying on just one type of tracking.” For similar reasons, a couple of different modeling groups have found that using wastewater data in tandem with other data sources, such as hospitalizations, tends to lead to more accurate predictions than using one metric on its own.
What do I do if there are no testing sites in my community?
I put this question to a few experts when working on this story, and Colleen Naughton (who runs the COVIDPoops19 dashboard) had a great response:
My recommendation would be to try to look at nearby sites since their site may experience similar trends. For example, if there is an increase in a site that is a major urban center near you then it may also be increasing your area, especially if people commute to that area. The state viral activity levels for the CDC NWSS can still be a good reflection of how the virus may be in that state compared to past trends. Also, if neighboring states are increasing that may be a sign that it could increase in your state soon.
What is the relationship between WastewaterSCAN, Verily, and the CDC?
Verily, a health tech company owned by Alphabet (Google’s parent company), helps to collect and test wastewater samples for both WastewaterSCAN and the CDC. Verily has worked with WastewaterSCAN for a couple of years, and became a contractor for CDC NWSS (replacing Biobot) last fall. The company also helps share data from WastewaterSCAN sites with the CDC.
In other words, the sites in WastewaterSCAN and the sites that Verily tests for its CDC contract are two separate groups of wastewater treatment plants. WastewaterSCAN sites are included in the CDC dashboard, but not the other way around.
What is the current funding situation for these programs?
The CDC NWSS team is working on expanding wastewater surveillance across the U.S., Kirby said in her statement to The Sick Times. CDC scientists are supporting state, local, and tribal health departments, while also working to develop standards (and the National Institute of Standards and Technology is working on standards, too).
However, the CDC and other health agencies need more funding to expand current testing programs and support them long-term. As I reported last year, CDC NWSS currently has funding through 2025, and will need more support after that. This piece at the COVID-19 Data Dispatch has more details about the funding landscape; note that it was written before the CDC changed contractors from Biobot to Verily.
When I asked for updates about CDC funding, Kirby shared: “The FY 2025 President’s Budget request includes $20 million in new base funding that will allow CDC to support a limited number of states for wastewater surveillance to continue public health laboratory capabilities and wastewater programs and allow innovation for detecting other infectious disease threats once supplemental funds are depleted.” Congress may also add wastewater surveillance support when it reauthorizes the Pandemic and All-Hazards Preparedness Act, a federal bill that expired recently; last year, three Senators introduced a wastewater provision to this Act.
What actions can we take to support more wastewater testing?
Readers interested in seeing continued wastewater testing can consider:
Ask your representatives in Congress to support CDC NWSS in the FY 2025 budget and through reauthorizing the Pandemic and All-Hazards Preparedness Act.
Encourage your state and local governments to fund wastewater testing at these levels. New York State offers one notable example: Governor Kathy Hochul included an expansion of wastewater surveillance in the state’s 2023 budget.
Ask your local wastewater treatment plants to get involved with testing. Public health officials or companies have to work with these plants to collect samples, which is often a “limiting factor” in expanding testing, Matus, from Biobot, said. Community members can reach out to these plants directly and let them know there is interest in testing, she said.
If you live in or have connections to Canada, consider signing this petition encouraging continued wastewater surveillance in Ontario. “We believe canceling this program is dangerous, short-sighted, and anti-science,” said a member of the volunteer group behind this petition in an email to The Sick Times.
All articles by The Sick Times are available for other outlets to republish free of charge. We request that you credit us and link back to our website.