The onset of colder weather and shorter days marks the beginning of the annual respiratory illness season, with COVID-19 cases already showing an upward trend. According to Dr. Anne Rimoin, a professor of epidemiology at the UCLA Fielding School of Public Health and director of the Center for Global Health Security, the current situation varies significantly by region. The West is experiencing a substantial increase, while activity is also climbing in parts of the Northeast and Midwest. Meanwhile, the South appears to be at a more advanced stage in its current wave.
Data from the Centers for Disease Control and Prevention (CDC) indicates that at least 12 states are currently reporting moderate to very high levels of COVID-19 activity. Furthermore, CDC Rt Estimates, which track the spread of seasonal respiratory viruses, show that infections are growing or likely growing in 27 states, while they are declining or likely declining in 13 states, and remaining stable in 10 states. Dr. Rimoin noted that this regional variation is not unusual, as COVID-19 waves often do not move uniformly across the country or peak simultaneously.
Wastewater testing serves as a critical early warning system for public health officials to identify potential outbreaks, even in communities where individuals may not be displaying symptoms. While the CDC reports low levels of COVID-19 nationally, data from WastewaterSCAN, a program operated by Stanford University, presents a different picture. According to Amanda Bidwell, the program's scientific manager, national COVID-19 levels in wastewater rose by 55% in September compared to August. Sites across the country continue to show an upward trend, with concentrations in the West and South having already surpassed levels observed during the 2025-2026 winter peak.
The tracking of SARS-CoV-2 levels in wastewater indicates that after reaching a low point in late spring, viral activity began to climb in July, with sharp increases throughout August and September. Health professionals emphasize that because COVID-19 and the flu share several symptoms, it is important to be aware of the overlap. Doctors recommend that everyone 6 months of age and older receive a COVID-19 vaccination during the flu season to bolster immune protection. Dr. Rimoin highlighted that because COVID-19 is a relatively new pathogen, it has not yet settled into the predictable seasonal patterns associated with influenza, leading to waves appearing at various points throughout the year.
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COVID-19 and the flu have several symptoms in common. Here's how you can tell between the two viruses:
