Do I still need to wear a mask in public? Is it safe to attend a concert or travel now? Experts rely on the COVID-19 pandemic to make such decisions. Reference to wastewater data is increasingly recommended. And they say the pandemic has revealed the true potential of monitoring what’s in our poop.
Wastewater monitoring is not entirely new. Epidemiologists have been using it to track polio outbreaks for decades, microbiologist Dr. Amy Kirby, program leader for the Centers for Disease Control and Prevention’s National Wastewater Surveillance System, told TODAY.com. Told.
Dr. Yingying Ye, assistant professor of civil, structural and environmental engineering at the University at Buffalo, told TODAY that before the pandemic, researchers knew that evidence of enteric viruses that infect the intestines could be found in wastewater samples. told com. .
It’s “no surprise” that viruses like the virus would be found in feces and sewage, Ye said. But before the pandemic, “people didn’t think they could use wastewater to track respiratory viruses,” she says. It wasn’t until COVID-19 emerged that experts realized how useful wastewater monitoring could also be in tracking other types of viruses, including respiratory viruses, she explains.
As other coronavirus monitoring tools we once relied on become less useful, wastewater is becoming increasingly valuable as a tool to help us make safer choices. Here’s what experts want you to know about wastewater monitoring for COVID-19 and what the numbers mean for you.
When did COVID-19 wastewater monitoring begin?
Early in the pandemic, separate groups of researchers demonstrated that they could detect the coronavirus in wastewater, particularly on university campuses.
For example, experts at the University of Arizona used wastewater to reduce the spread of infection on campus in August 2020. In 2021, a group at Emory University used wastewater to discover an increase in COVID-19 infections on campus as students returned from the spring. break.
From there, the CDC began monitoring wastewater for COVID-19 in 2020 (which Kirby said was the first widespread wastewater monitoring program in the United States) and ramped up the program in 2022.
Currently, wastewater monitoring is also helping researchers monitor other diseases such as Mpox, norovirus, and hepatitis A.
What does COVID-19 wastewater data actually measure?
When a person is infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), some of the virus is shed in the feces, whether or not there are any noticeable symptoms. That’s why the CDC began considering wastewater surveillance for the coronavirus in the first place, Kirby said.
“We really focused on how can we better understand people who are infected but may not have symptoms or may have very mild symptoms,” she says. . “We know they will continue to shed the virus in their faeces, so we can detect those cases (through wastewater monitoring) and see how they impact overall trends in the community. can.”
Yeh and Kirby noted that researchers still don’t fully understand why this respiratory virus is shed in our stool. Kirby said it could be the result of swallowing virus particles in respiratory secretions or the virus replicating in the intestines, similar to food poisoning.
“We don’t know, but for our purposes it doesn’t really matter,” Kirby explains. “We know that it’s there and that it’s a great signal to understand what’s going on in the community.”
As it turns out, wastewater not only reflects general trends in the spread of COVID-19 within communities, but it does so relatively quickly. Throughout the pandemic, Kirby said, experts have noticed changes in wastewater trends four to six days before the same changes in case numbers and test positivity rates.
“This is really the first sign that cases are starting to rise in the community,” she said. “This is also the first sign that the number of infections is starting to decline,” which is a big advantage compared to other indicators.
Yeh, whose team is monitoring coronavirus wastewater across much of Western New York, said experts are using a well-known test, polymerase chain reaction technology (PCR), to detect viral RNA in untreated wastewater. Explain that you are looking for. Depending on the type of PCR test researchers use, they can also look for changes in the genetics of the virus, which can alert them to possible changes in mutant strains of the coronavirus.
The protocols for detecting virus particles, analyzing the data, and making sure the results are accurate can vary from lab to lab, Holger says. For example, if rainwater is diluted by heavy rain, it can be difficult to account for in interpretation, he says.
Ye emphasized that public health officials only consider this data at the community level. They do not monitor wastewater at the individual or household level. (No one is tracking what you are spouting as an individual.)
And just to be clear, researchers believe the virus particles in feces are inactive, Ye says. To date, no one has contracted COVID-19 from exposure to wastewater, according to the CDC.
Why is wastewater monitoring so useful today?
Previously, we may have relied on case counts and test positivity rates to assess how much and how quickly COVID-19 was spreading in our region.
But these metrics “are not very useful anymore,” Holger said. There are two main reasons for this. First of all, many people are no longer being tested for COVID-19 at all. And second, if you do get tested, it will likely be a rapid home test and will not be reported to public health agencies.
However, one of the big advantages of wastewater monitoring, he explains, is that “there is no need for an individual to do the testing.” “We’re just tracking what’s going on in the community.”
Wastewater data also has the advantage of being very local, so it’s relevant to what’s happening in your area, Yeh says.
Use COVID-19 wastewater data to guide your actions
To find COVID-19 wastewater monitoring data in your area, visit your local public health department’s website. The CDC also tracks local and national wastewater counts.
“There are approximately 1,500 testing facilities, covering more than 40% of the U.S. population,” Kirby said. “So we’re covering a large portion of the population.”
That said, if your area doesn’t have local wastewater monitoring, Holger recommends paying attention to national or state-level numbers. “When things are getting worse nationally, there’s a good chance things are getting worse locally, or are getting worse locally,” he says.
But local information is always most helpful, Yeh said, noting trends can vary from county to county. And rural areas, which are often not connected to large-scale wastewater systems, may not be included in these estimates, she explains. Researchers are currently working on ways to reach these areas, she says.
Also, keep in mind that the numbers you see on your dashboard may lag a week or two behind what’s actually happening in your community, Hoerger says. For example, Ye said lab samples are typically collected once or twice a week, and those numbers are included in the health department’s update the following Monday or Friday.
It’s not entirely clear how wastewater counts translate into the actual number of cases in a community. However, spikes in wastewater monitoring typically show similar spikes in actual COVID-19 cases.
“There’s no direct correlation,” Kirby explains. “(But) when we see that the wastewater concentrations have doubled, we see that the number of infections in the community has also doubled.”
Experts say if your numbers are starting to increase, it may be a sign it’s time to take additional precautions, including:
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If you previously stopped wearing a mask, start wearing it again in public places (such as public transport).
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Get the latest vaccine or booster if you’re eligible.
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Skip or limit crowded indoor events. Or, if you’re hosting an event, consider taking it outside.
Additionally, while traveling, Ms. Ye checks the wastewater trends of her destination and plans what precautions she needs to take.
When you look at the data, Kirby says, you don’t have to think too hard about what the specific numbers mean. “Focus on trends, not levels,” she says. “That’s the best way (for the general public) to interpret that data.” The CDC’s wastewater trends dashboard is designed to be intuitive and will be used for exactly this purpose, she added.
Both Kirby and Yeh recommend thinking of wastewater monitoring data for your health “like a weather forecast.” In the future, Ye hopes, “we can use wastewater data as a kind of prediction to tell us whether we are likely to get infected with the coronavirus tomorrow.”
For now, Kirby wants people to look at the data and decide whether they should wear masks on public transport or scale back things like indoor events. Incorporating this type of decision-making into daily life “will go a long way toward keeping our communities healthy,” Kirby says.
This article originally appeared on TODAY.com
