U.S. sees early rise in COVID-19 cases as summer wanes, experts warn of possible September peak
CDC data show COVID-19 infections increasing in all states, with the West and South reporting the sharpest upticks; health officials say the wave is modest compared with last year but could peak in early September.
COVID-19 cases are climbing across the United States after a quiet spring, with the Centers for Disease Control and Prevention reporting growth in all 50 states as of Aug. 12. The increase is most pronounced in the South and West, where wastewater monitoring shows a significant rise in viral concentrations since late June.
"The national data is beginning to tick up, but it’s not a substantial increase yet," said Dr. William Schaffner, an infectious-disease specialist at Vanderbilt University Medical Center. WastewaterSCAN, a Stanford University monitoring program, reported that SARS-CoV-2 levels in wastewater are up 106% compared with July, and that the West and South have the highest concentrations.
At least 15 states and territories are experiencing active outbreaks, according to the Pandemic Mitigation Collaborative. However, experts note that current viral loads are lower than during the intense summer surge driven by the “Stratus” variant in 2025, when test positivity exceeded 9%. This year, weekly positivity is around 4%.
The dominant strain, identified as XFG.1.1, accounts for roughly a quarter to two-fifths of recent cases, while the BA.3.2 (Cicada) variant makes up about 15%, according to CDC data. "It’s still within the family of past omicron variants, so it’s not a big jump in terms of being different," said Dr. Albert Ko of Yale School of Public Health.
Symptoms remain similar to earlier omicron infections, including cough, sore throat, fever and fatigue. The CDC advises isolation until symptoms improve and fever-free for at least 24 hours without medication, and recommends mask use and social distancing for vulnerable contacts.
The Food and Drug Administration has recommended an updated COVID-19 vaccine targeting the XFG variant for the 2026-2027 season, though distribution is not expected until September. Health officials encourage eligible individuals, especially high-risk groups, to discuss booster options with their providers.
"We need to be very cautious. We’re still only in the middle of August," Schaffner added, noting that back-to-school and summer travel could facilitate further spread.