As the U.S. enters the fall season, a late-summer COVID-19 wave is driving rising coronavirus cases and increased viral activity across nearly every part of the country, according to data from the U.S. Centers for Disease Control and Prevention. While national health officials emphasize that overall COVID activity remains low, infections are growing or likely growing in 47 states as of September 2, 2026, prompting localized school closures and a notable jump in wastewater viral concentrations.
Wastewater Monitoring Reveals Broad Viral Spread
SARS-CoV-2 concentrations in wastewater jumped 140% nationwide in late August compared to July 2026, according to Amanda Bidwell, Scientific Program Manager for WastewaterSCAN, a Stanford University-run infectious disease monitoring program. Bidwell noted that in the West and South, viral concentrations have actually surpassed the peak levels observed during the 2025-2026 winter wave.
According to CDC data for the week ending August 29, 13 states are reporting moderate, high, or very high levels of COVID-19 activity in wastewater systems. These jurisdictions include Alabama, Alaska, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, Montana, Nevada, Texas, and Washington. Texas is currently reporting the highest levels of COVID in wastewater of any state. The rapid local spread forced the San Perlita Independent School District in south Texas to shut down from August 25 to August 26 to protect the health and safety of students and staff.
Michael Hoerger, Ph.D., an assistant professor at Tulane University School of Medicine who leads the Pandemic Mitigation Collaborative, reported that at least 29 states and territories were experiencing active COVID outbreaks by August 31. He called the widespread transmission troubling for residents living in those high-activity areas.
Comparing the 2026 Late-Summer Wave to Prior Surges
Despite the sharp uptick in wastewater metrics and climbing case counts, infectious disease experts point out that the current wave appears to be less severe than previous outbreaks. In 2025, the United States experienced an intense summer surge driven by the “Stratus” variant that persisted into the fall season. By contrast, SARS-CoV-2 concentrations remain lower overall than at this same point last year, according to WastewaterSCAN data.
Test positivity rates also reflect a milder trajectory. During the week ending August 29, roughly 6% of COVID-19 tests returned a positive result, down from a weekly test positivity rate of over 11% during the same period in 2025, per CDC tracking. Dr. William Schaffner, an infectious disease specialist and professor of medicine at Vanderbilt University Medical Center, explained that the virus has settled into a distinctive seasonal pattern since the start of the pandemic, featuring two waves each year in the middle-to-late summer and during the winter.
While the country focused heavily on a massive outbreak of the foodborne pathogen cyclospora last month, coronavirus cases began quietly creeping upward just in time for the back-to-school season. Public health authorities advise anyone experiencing coughing, sniffles, or related respiratory symptoms to take a COVID-19 test to confirm their status and prevent further community transmission as national peak transmission windows approach.
Keep reading