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October 4, 2022

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How UNLV researchers can use sewage to help inform public health policy

UNLV Waste Water Team

Wade Vandervort

Edwin Oh, Ph.D., Associate Professor at the Kirk Kerkorian School of Medicine, right, and undergraduate research assistant Nabih Ghani demonstrate their process for collecting a wastewater sample at UNLV Tuesday, Jan. 11, 2022.

UNLV Wastewater Team

Lab technician Liz Dahlmann removes a manhole cover at UNLV during a demonstration of how wastewater samples are collected Tuesday, Jan. 11, 2022. Launch slideshow »

Edwin Oh, an associate professor at the Kirk Kerkorian School of Medicine at UNLV, was among the first to discover the omicron variant in Clark County.

But he does not work at a COVID-19 test site.

He examines manholes — and in them, the wastewater and first sewage samples that captured omicron one week before the county reported its first human case of the highly transmissible variant on Dec. 14.

Oh ​​leads the wastewater surveillance program at UNLV, where he found omicron displacing delta in the wastewater in up to 9 out of 10 infections. The virus is shed in human waste, like fecal material, making sewage from humans a prime place to observe the virus and its variants.

Oh watched each strain of the virus come and go, from the original Wuhan strain to delta and now to omicron. He said wastewater monitoring is essential in informing policymakers to enact effective public health policy such as widespread testing, and empowering residents with information to keep them safe.

We talked to Oh about this and more. Here are some highlights from our conversation, which are edited for clarity and brevity.

What is wastewater data showing us about the omicron variant right now?

We first discovered the omicron variant in wastewater on Dec. 7. This was from a sample that was coming in from the Strip, and so to us, this was a really interesting observation because we’ve never had an opportunity to localize variants with this type of specificity before. Since that time, we’ve seen the first clinical case show up, one week later, and we’ve seen levels of the variant increase in various communities across Southern Nevada. Unfortunately, what we’re seeing now in human cases and human infections is a reflection of what we were able to observe from wastewater. ... Rather than waiting for people to show up at testing centers, we have that information that’s collected in a very deidentified manner, that we can protect the privacy of homes of families of communities, and folks don’t even need to get tested. So I think it fills a really large gap that we’ve seen previously in clinical testing, where we might run out of tests, or folks might not be very motivated to get tested.

How long have you been doing wastewater testing?

Primarily for COVID, we started back in March and April (of 2020), together with Dr. Dan Garrity, at the Southern Nevada Water Authority. I’d like to emphasize the collaborative partnership that we have going here with the water authority. None of this would have been possible if it weren’t for folks in the water authority. We’re working together on a grant for wastewater surveillance for underserved and vulnerable populations (with the health district). ... It’s been two years of constant sampling and learning and working on this project. A lot of us here have not taken a vacation in almost two years. It’s been a lot of time and energy dedicated toward a better understanding of how this pathogen is going to evolve over time.

What is the process to test the wastewater, and how do you specifically look for the COVID variants?

There are at least two different levels that we can collect and analyze the samples: One is by going out to the wastewater treatment plants, where you can have a plant that services 50,000 people or 800,000 people. The second level is that we can go straight to manholes and get sewage that’s coming from a building or a number of buildings. We can look at a respiratory pathogen like SARS-CoV-2, but we can also look at a whole host of other respiratory pathogens and pathogens in general, as long as these show up in fecal material and/or urine. I can see a day in the future where we have sewage that we collect from elementary schools, where we can get a sense of norovirus or stomach flu, and this information can be something we can act on to prevent outbreaks that end up closing schools. This is intelligence that we can gather and we can plan policy around, and that policy can include the deployment of public health resources.

Tell me more about any public health policy that would benefit Clark County.

This is this is an ongoing conversation and debate, really across the country and around the world: With this new information, how can we now develop policy so we can limit the effects of a pandemic when it happens again? Two years ago, we didn’t have this type of surveillance program in place. Within the past two years, many folks across the country have improved on some of these tools, and we can ask these types of questions with a lot more precision now. We may run into a situation where we asked for all participants or workers to be vaccinated, but we might encounter a new strain that is resistant to these vaccines. So with wastewater surveillance, we’ll know whether folks are infected by this newer strain, and then we can then decide: Do we transmit this information to folks in the building? Do we run contact tracing with this type of information? Traditionally, contact tracing is done in a manner that’s dependent on individuals who report that they’ve been infected.

It’s very reactive rather than preventive.

Right. Here, we’re taking proactive measures to delay, to prevent, to decrease, to limit the impact of some of these potential disasters.

Are there any other best solutions to tackling COVID right now, specifically for Clark County?

We have the science in place right now to come up with these numbers and predictions. The goal is to figure out how we can integrate all of this information. How can we get this program in place for, let’s say, the airport? For the Strip? For places where you would typically see tourists? Again, the goal here isn’t to close any business down: The goal is to be able to get that information so if we need testing kits to be deployed, we will have that information whether to do so or not, versus being reactive and waiting for what we know will happen to happen. The types of policies that you’d want to think about should take the demographics into consideration.

If effective policy will be based on demographics, do you imagine that a lot of the policy change would happen locally or on a state level? Or how much of this needs to also happen on a federal level?

I think federally. What would be important is to push for national wastewater surveillance programs. How you then act on some of this information is going to be more relevant depending on the cities where you live. If you have a city that’s very young and very mobile, go in and run wastewater surveillance and say, ‘Look, you have high levels of the virus circulating in the community, everyone needs to be quarantined.’ That type of prescription probably wouldn’t be too helpful because folks won’t accept such recommendations. When we run wastewater surveillance for dormitories, we don’t tell students to just quarantine, don’t move for 10 days and stay in your room. The recommendation across the country is to provide this information, and empower individuals so they can be a little bit more responsible, get tested and stay vigilant if they know that Building A versus Building B has more virus in circulation.