CDC: Sewage systems showing increased levels of COVID

(CNN) - Could we see another rise in COVID cases nationally?

That has become a concern recently, with more and more sewage systems in the U.S. detecting increased levels of coronavirus.

The Centers for Disease Control and Prevention reports nearly 40 percent of wastewater sampling sites are reporting an increased level of the virus over the past 15 days – doubling the numbers from last month.

Wastewater data cannot estimate the number of cases in a community. Still, the agency says monitoring this kind of data can be an early warning sign of increased transmission.