Wastewater Testing May Help Predict Coronavirus Hotspots

John Whyte, MD, MPH; Mariana Matus, PhD


June 24, 2020

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  • SARS-CoV-2 sheds in the stool of infected individuals and therefore finds its way into the wastewater infrastructure.

  • Wastewater data tend to predict a number higher than the reported clinical cases of SARS-CoV-2 and correlate with future cases of the virus.

  • Currently, there is no evidence that coronavirus present in wastewater is infectious.

  • Wearing proper PPE when handling wastewater is still recommended.

This transcript has been edited for clarity.

John Whyte, MD, MPH: You're watching Coronavirus in Context. I'm Dr Whyte, chief medical officer at WebMD.

We've had a lot of discussion over the past few weeks about how to diagnose whether someone has COVID-19. How common is coronavirus in the community? Is analyzing stool and waste one of the ways that we can measure this?

I've asked Dr Matus, who is the CEO and co-founder of Biobot Analytics, to help answer these questions.

Dr Matus, thanks for joining me.

Mariana Matus, PhD: Thank you for the invitation. Happy to be here.

Whyte: We've heard a lot in the past about finding opioids and prescription drug residue in sewage. Now we're hearing about COVID in wastewater. What's the latest?

Matus: The novel coronavirus is shedding in the stool of infected individuals and therefore finds its way into the wastewater infrastructure. We collect wastewater samples, look for the virus, and understand approximately how many people are infected in that area.

Whyte: Have you been doing this in certain cities?

Matus: Yes. Back in March, our team was the first one to detect the virus in wastewater in the United States. Shortly after, we opened a pro bono campaign, inviting wastewater treatment plants to send samples every week. We ended up analyzing close to 2000 samples from 400 wastewater treatment plants enrolled in the program, representing 42 states and 10% of the US population.

Whyte: So is it correlating with antibody studies and diagnostic tests? How are folks using the data from an epidemiologic perspective to understand how prevalent the virus is in the community?

Matus: That's a great question. When we first started, we were comparing the estimates from the wastewater with cumulative cases in that community to how many people have been diagnosed with COVID-19. We found that the wastewater data tended to predict a higher number than reported clinical cases of COVID-19, which created this mystery of what's happening, because we are consistently seeing higher numbers as predicted by the wastewater.

Further research has shown that the wastewater data better correlate with future coronavirus cases. It has a little bit of a lead time into new clinical cases.

Whyte: There are no data to suggest that the wastewater is infectious with the coronavirus. Is that correct?

Matus: That is correct. It is very important for everyone to understand and hear about. So far, there's no evidence that the virus found in human stool, in human waste, is infectious. Therefore, by extension, there is no evidence that the virus present in the wastewater is infectious. There's a proper study going on at the moment, organized by the CDC, so we should hear more about that soon. But so far, all of the evidence points out that the coronavirus is inactive.

Whyte: We don't want people who are watching this to think they could catch the coronavirus by coming in contact with stool, either at a public restroom or a friend's bathroom. Is that right? I don't want to misinform anyone.

Matus: Correct. For now, we should not make assumptions about that.

Whyte: There are other reasons why we should practice good sanitation.

Matus: We still recommend wearing proper PPE when handling wastewater, keeping proper hygiene at home, or even increased hygiene at home. But no, there's no added risk known at the moment.

Whyte: Certainly increased hygiene, hand washing, cleaning bathrooms.

Where do you think we'll be 6 months from now in looking at wastewater? Will it be even more prevalent? Will we be relying more on antibody testing? Why do you think it isn't being used more right now?

Matus: Well, I think that over the next 12 months or so, we will see huge adoption of the wastewater data together with the other pieces of the puzzle, the other types of surveys. Our vision is that every city and every state in the country should be looking at wastewater data. Our company has decided to support this service over the next 12-24 months, because we see a lot of interest and a demand to have this as an ongoing tool. I think that what's going to happen is more people are going to start making dashboards and models that look at the different types of information ─ antibody testing, clinical testing, random testing, wastewater data ─ and painting a more holistic picture of what's happening. It's not only government and public health officials; we also see a lot of interest from places of work, like universities, dorms, nursing homes, that want to have an early warning for a new outbreak in their communities.

Whyte: Thank you for sharing this very interesting information. We'll be learning more over the next couple of months.

Matus: Thank you.

Whyte: Thank you for watching Coronavirus in Context.

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