COVID clues in the wastewater

March 28, 2022

In February, the Center for Disease Control and Prevention’s (CDC) COVID Data Tracker released a Wastewater Surveillance tab, which tracks changes and detections of SARS-CoV-2 viral RNA levels at more than 600 testing sites across the country.

Because many people with COVID-19 shed the virus in their feces, wastewater testing can help with monitoring COVID-19 in communities. Virus levels in wastewater usually increase four to six days before clinical cases increase, so surveillance results can help communities act quickly to prevent the spread of COVID-19.

Currently, virus levels in wastewater are relatively low across the country. More than half of all sites reporting wastewater data are experiencing a decrease in SARS-CoV-2 levels, but some have reported a modest uptick. These upticks may reflect minor increases from very low levels to levels that are still low. It’s important to note that even a small increase when levels are very low can appear like a dramatic increase in the percent change. However, there is a possibility that some communities might start to see an increase in COVID-19 cases. This could happen for a variety of reasons, like waning immunity, new circulating strains, and eased prevention strategies.

Right now, it’s too early to know if we’ll see a corresponding increase in reported cases across the country. Wastewater data are meant to be used with other COVID-19 surveillance data. CDC encourages local public health officials to watch for sustained increasing levels of the virus in wastewater, and to use wastewater surveillance data with other kinds of data to inform their decisions. CDC continues to encourage people to use COVID-19 Community Levels to find out what actions they should take to protect themselves and others. The whole community can be safe only when we all take steps to protect each other.

CDC Release

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