COVID cases are rising in some states. See the map - USA Today
With colder weather on the way and days growing shorter, the annual respiratory illness season is beginning to take shape. COVID-19 cases are already trending upward.
The Centers for Disease Control and Prevention categorizes COVID-19 viral activity in wastewater as "low" nationwide, based on its latest available data. However, several states, particularly in the South and West, have reported high or very high activity levels.
"Right now, the picture is quite different depending on where you are: The West is seeing a substantial increase, activity is also rising in parts of the Midwest and Northeast, while the South appears to be further along in its wave," said Dr. Anne Rimoin, professor of epidemiology at the UCLA Fielding School of Public Health and director of the Center for Global Health Security.
According to CDC data, at least 12 states were experiencing moderate to very high levels of COVID-19 activity.
Wastewater testing is designed to serve as an early warning system for public health officials, helping them identify and respond to potential outbreaks.
Even when people in a community are not showing symptoms, wastewater, or sewage, can be tested for signs of infectious diseases. CDC data can help detect changes in disease activity levels within a state.
While the CDC reports low levels of COVID-19, data from WastewaterSCAN, a wastewater surveillance program operated out of Stanford University, indicates that COVID-19 activity remains high nationwide and has risen sharply in recent weeks.
The chart below tracks SARS-CoV-2 levels detected in wastewater nationwide. After reaching a low point in late spring, viral activity began rising in July and climbed sharply through August and September, indicating increasing COVID-19 transmission.
"In September, national COVID-19 levels in wastewater are up 55% compared to August," according to Amanda Bidwell, WastewaterSCAN Scientific Program Manager. "Sites are continuing to trend up across the country. In the West and South we’ve surpassed the COVID-19 concentrations observed during the winter peak (2025-2026)."
According to CDC Rt Estimates, which measure how quickly seasonal respiratory viruses are spreading, COVID-19 infections are growing or probably growing in 27 states, declining or probably declining in 13 states, and remaining unchanged in 10 states.
"The regional variation is not particularly unusual," Rimoin said. "We've seen this repeatedly with COVID. Waves don’t necessarily move across the country in a uniform way or peak everywhere at the same time."
Doctors and health professionals are recommending that everyone 6 months of age and older get vaccinated against COVID-19 during the flu season because the symptoms overlap. Your immune system may be weakened by one infection, leaving you more vulnerable to others.
COVID-19 and the flu have several symptoms in common. Here's how you can tell between the two viruses:
"We’ve seen COVID increasing in late summer and early fall before, so an uptick at this time of year is not particularly surprising," Rimoin said. "COVID is still a relatively new pathogen and has not really settled into the kind of predictable seasonal pattern we see with influenza. It continues to produce waves at different points throughout the year."
