What wastewater samples tell us about AZ COVID-19 cases — and what else officials are looking for

The CDC says the Western region has the highest level of COVID-19 activity in the country right now based on wastewater testing.

California, Nevada, Utah and Colorado all have high viral activity levels, but the agency says Arizona’s level is very low.

To learn more, The Show spoke with Reshma Neupane, food and water borne and wastewater surveillance program manager at the Arizona Department of Health Services.

Full conversation

MARK BRODIE: Reshma, broadly speaking, what are you seeing right now, in terms of COVID numbers in Arizona?

RESHMA NEUPANE: Yeah. So in regards to the wastewater levels for COVID-19 that we're seeing here in Arizona, it's currently trending low. Having said that, we are, you know, monitoring, continuing to monitor the trends and, seeing if there is going to be an increase or decrease, with it across the state.

And just wanted to remind that these are, you know, levels where we are testing for wastewater and then in addition to just using wastewater data, we do highly encourage that. We do use wastewater data with additional public health surveillance data. For example, the case data has analyzation. So that's what we try to do in case of, you know, using just solely wastewater data, but kind of incorporating that with additional public health data.

MARK BRODIE: Well, I'm curious, like in terms of to the extent that we get the numbers that we get, how much of that is because of wastewater, like, I just wonder how much other testing is going on beyond what you are finding, you know, people not necessarily testing for it, but, you know, the virus showing up in the wastewater.

NEUPANE: Yeah. So, you know, with wastewater surveillance, we are able to kind of see, you know, what's circulating the virus that’s circulating within the community. And just, you know, I do want to reiterate that, these are sites where we are just waiting, you know, testing for wastewater because there are other sites that we're not currently monitoring.

So what we can pick up in wastewater is, you know, if people don't go out there to get tested, visit their doctor. So that's where we're kind of picking up and wastewater and that's the, you know, and when we collect those samples and send it off to the laboratory for testing, that's what we're essentially kind of, you know, testing for those viral levels in that sample. So that's what, you know, essentially we're seeing in wastewater compared to other, other, surveillance data that we see for example, for COVID-19.

BRODIE: How much wastewater surveillance testing is Arizona doing right now?

NEUPANE: So we are testing, Mark, in terms of Arizona, we're monitoring wastewater within 26 sites. And that kind of goes over a couple of couple counties that we're testing for statewide.

BRODIE: And do you have a sense of how that compares with other states, like is Arizona doing more wastewater surveillance, other places or less, or about the same?

NEUPANE: I think it kind of depends on what other states are kind of, have brought on in terms of how much they're expanding in terms of pathogens. On our end, we're currently testing for COVID-19. Flu-RSV and anything that is positive for Influenza A or a subtype for H5. But like I said, I think it definitely depends on what other states are planning to bring on and how much they're expanding. And that that differs state by state.

BRODIE: Are the levels of the other pathogens for which you're testing also fairly low in Arizona right now? 

NEUPANE: Yes. In terms of the other, other pathogens that we're testing for and currently have data for, yes, they are trending low at this time.

BRODIE: Would you expect that to continue? I mean, are you anticipating a rise in anything, you know, in the coming weeks or months?

NEUPANE: Yeah, it's hard to say. I mean, and definitely depends. I'm not sure what the upcoming respiratory season is going to bring on to us. But we are definitely on, on the lookout. And we do monitor very closely, especially during the respiratory season.

BRODIE: Are there plans to continue doing the level of wastewater testing the state is doing going forward?

NEUPANE: That is the hope, yes. We are continuing to maintain what we're testing for at this time.

BRODIE: When you say hope, I mean, is that dependent on funding or dependent on policy or something else?

NEUPANE: It is definitely dependent on funding. And, you know, we currently have CDC funding that we use for our wastewater surveillance program. This tool really lets us see what's circulating within our community. You know, often before, you know, people get sick or tested.

And, you know, it definitely has that potential for it to be an or an early warning system that can help us kind of track trends, monitor trends, and hopefully respond earlier to, you know, any diseases or emerging diseases, and pathogens and kind of act as an additional tool for our public health surveillance so that we can, like I said, monitor trends, but also, you know, make sure that we have a timely public health response.