Host: Anna Mehrotra
Guest: Amy Kirby | National Wastewater Surveillance System Lead | Centers for Disease Control and Prevention (CDC)
Category: 🔬 Research
Podcast’s Essential Bites:
[12:44] “The National Wastewater Surveillance System was established by [the] CDC in September of 2020. And the goal was really to provide community level data to track COVID-19 infections. And there are four big advantages to wastewater surveillance. First, it provides information on asymptomatic infections, as well as symptomatic infections. And importantly, these days, it also provides information on unreported cases. So as we see more and more people using rapid tests and home testing, those aren't reported to our health departments. So we don't know through the clinical testing system about those positive tests. But those people will still be shedding virus in their stool, and we can detect those cases through wastewater surveillance.”
[13:32] “Second, it is independent of healthcare seeking access. So it doesn't matter if an infected person goes to the doctor or gets tested or has access to testing. […] Third, it's efficient. So one sample at a wastewater treatment plant can represent hundreds, thousands, even millions of people in our largest systems. And finally, it's fast. From the time the toilet is flushed until the time we have data in hand is about five to seven days. And that means we have a lead time over clinical surveillance of a week to two weeks, depending on where we are in the pandemic. So it is an early indicator of presence and trends and infections in the community.”
[15:16] “We have seen this data really be used very widely by our health department partners. So they're using it to make decisions about resource allocations, looking at how different communities in their jurisdictions are performing. […] And importantly, […] they value wastewater surveillance because it increases their confidence that they really know what's going on in their communities in this very dynamic and fast moving pandemic, where conditions change quickly, and wastewater surveillance gives them that extra confidence, that they really understand what's going on.”
[16:22] “It wasn't until the emergence of Omicron, that we've really seen these variant tracking methods work in practice, to really show that we can track the emergence of a new variant of concern in communities in the US through wastewater surveillance. […] In many of those communities, the detection in wastewater was prior to any detection in clinical cases. So it is serving as that first warning.”
[33:36] “There are models that people have developed that will allow you to take those wastewater concentrations and estimate community prevalence, what percentage of people are infected. The problem with those models is that we don't have all of the data that we need to what we call parameterize the model, so flesh out all of the pieces. And so what you end up with is an estimate that's very uncertain, and can span several logs. […] We are hoping that they will continue to converge and get better. And we'll be able to make that conversion sometime in the future. But for right now, it's just not something we can do.”
[38:40] “When I talk about wastewater surveillance, where it can be helpful [is] in low incidence periods to detect reemergence. So are we seeing infections come back up in a community, or emergence of a new variant, as we've seen for Omicron. But when we know that the infection is prevalent in a community, then what wastewater surveillance is really useful for is tracking the trends. […] I expect that wastewater surveillance will play a really critical role for us in understanding when we are actually past the peak of Omicron.”
[44:29] “We have a variety of lines of data suggesting that the virus does not survive treatment. […] We really don't have any evidence that infectious viruses are present in raw wastewater at any consistent and substantial level. […] Most of our common disinfectants will inactivate this virus very, very quickly. And that's just thinking about wastewater treatment. So when we get to drinking water treatment, and we add additional treatment in our drinking water system, and disinfection, either with something like ozone, or chloramines, or chlorine, that is going to be very, very effective in removing any very low levels that may even enter the drinking water system. And so all of that comes together to say that we really don't expect there to be any risk of potential SARS-CoV-2 in drinking water.”
Rating: 💧💧💧
🎙️ Full Episode: Apple | Spotify
🕰️ 47 min | 🗓️ 01/18/2022
✅ Time saved: 45 min
