Why Scientists Are Looking At Wastewater To Detect COVID-19

As the Omicron BA.2 variant makes its rounds around the globe, health experts are monitoring wastewater to uncover warning signs about a potential rise in infections. ABC News reports that the Centers for Disease Control (CDC) has already discovered, in recent weeks, at least a 100% uptick in traces of COVID-19 in 37% of the wastewater sites that the nation's health protection agency monitors. Nearly 30% of the sites saw at least a 1,000% increase.

"It is likely we will see a new rise in cases across the United States as our wastewater data is showing a concerning signal," Rebecca Weintraub, assistant professor of global health and social medicine at Harvard Medical School, told ABC News.

Gathering data from wastewater has been a key public health tool to determine the spread of coronavirus variants since the CDC launched the National Wastewater Surveillance System (NWSS) in September 2020. This is because those who are infected with COVID-19 and are either asymptomatic or unable to get a test are not included in official infection counts. However, those who are positive can shed the virus in their stool, so examining wastewater provides more accurate data about the spread of the virus (via Smithsonian Magazine).

Yet, the CDC's wastewater insights combined with the agency's latest COVID-19 guidelines send mixed messages. According to CNN, many counties that have seen a large uptick in the virus in its wastewater are areas that no longer require indoor mask-wearing. For instance, only four out of the 28 wastewater sites on the CDC's dashboard that showed a 1,000% increase in recent weeks have been described as having a "high" community level of the virus where indoor masking is still recommended.

According to CNN, the CDC pointed out that wastewater analysis is meant to complement other monitoring tools the agency is using to understand the spread of the virus. And while wastewater monitoring isn't yet tied to the CDC's latest guidelines, Amy Kirby, program lead for the National Wastewater Surveillance System, suggests that public health officials could still use data about rising levels to recommend standard preventative measures such as vaccinations and social distancing.

More sites representing more people across the country have been added ​​since the national dashboard was launched, and the CDC continues to add new sites. Newsha Ghaeli, president and co-founder of Biobot Analytics, tells CNN, "We are going to have another public health crisis — it might not be as severe as Covid-19 — but we are going to have public health emergencies as a society, and so wastewater [epidemiology] being established today can really help us in the future."