Just as Americans are dealing with the tail end of the "summer surge," the fast-approaching respiratory illness season has COVID-19 on the minds of health care providers once again.
The United States experienced a cycle of rising cases in the late summer, part of a multi-year pattern colloquially called the "summer surge." Another seasonal uptick is expected come fall as cold and flu season starts in October, experts previously told USA TODAY.
Data from WastewaterSCAN, a Stanford University-led tool that tracks disease presence by testing wastewater samples nationwide, shows that COVID-19 is in the “high” category as of Sept. 18, with August levels up 168% compared with July. Concentrations of the coronavirus detected in wastewater have doubled
each month since June.
The CDC, on the other hand, categorized activity as "low" nationwide, though its data is less up to date. Several states had "high" or "very high" activity, concentrated mostly in the South and West.
"We do seem to be seeing a slight decline, but there continues to be week-to-week variation," Dr. Andi L. Shane, Chief of the Division of Pediatric Infectious Disease at Children’s Healthcare of Atlanta and professor of pediatrics at Emory University School of Medicine. "While it is difficult to predict what we will see in the coming months, our plan is to be prepared for increases, especially as we prepare for the respiratory viral season."
Here's what to know about the latest data.
See map of where COVID-19 activity is high
One way the CDC tracks infectious disease is through wastewater monitoring. Wastewater, or water that has been used by humans, can come from sources like toilets, sinks, showers, manufacturing plants, businesses and storm runoff, and contain pollutants, organic matter, pathogens, and whatever else was introduced to it by people.
Nationally, COVID-19 viral activity was categorized as "low" by CDC wastewater data the week ending Sept. 12. It was "high" or "very high" in Texas, California, Washington, and Florida.
What is the most common COVID-19 variant?
The CDC has transitioned to using a longer timeframe to release model-based projections about COVID-19 variants because of low reporting from states.
According to the CDC's latest data projection for the four weeks ending Aug. 1, variant SW.2 was the most common, accounting for 21% of cases, followed by XFG.1.1 at 16% of cases.
WastewaterSCAN noted the most prominent strain as XFG, which was present in 65% of samples analyzed on Sept. 12.
XFG is a variant of Omicron and was first detected in Southeast Asia in January 2025. It has several sublineages (XFG.1.1, XFG.14.1, etc.) and was responsible for the majority of cases last year, accounting for at least 70% in August 2025.
BA.3.2, better known as "cicada," also tends to appear on infection lists and has been detected in wastewater, though still in low concentrations.
Most strains carry similar symptoms, said Shane, including body aches, chills, congestion, cough, runny nose, fatigue, fever and headache. BA.3.2 has been associated with a symptom called "razor blade throat," or an exceptionally sore throat. Some strains also carry a higher likelihood of stomach issues, infectious disease specialist at Stony Brook Medicine Dr. Luis Marcos told USA TODAY.
"There are other symptoms that COVID may present, not just cough or shortness of breath," Marcos said. "It can also present with GI symptoms like vomiting and diarrhea."
Can you get a COVID-19 vaccine?
Pediatricians' offices, Departments of Public Health, and retail pharmacists have COVID-19 vaccines available, Shane said. "The COVID-19 vaccines are approved for people age 65 and older as well as for anyone with a condition that puts them at high risk of severe illness," Shane said. "People who wish to get vaccinated but don’t qualify as high risk may also be able to receive a COVID-19 vaccine."
Until 2025, COVID-19 vaccines carried a broad recommendation for most Americans. That changed when Health Secretary Robert F. Kennedy Jr. removed healthy children and pregnant women from the CDC's recommended schedule, breaking with expert guidance.
The FDA later approved updated COVID-19 vaccines only for adults 65 and older and younger people with underlying health conditions, a policy that remained in place for 2026. As of Sept. 3, the CDC recommends the 2025-26 COVID-19vaccine through shared clinical decision-making, meaning people should consult a health care provider to weigh the benefits and risks based on their individual circumstances.
CVS, one of the most popular retail pharmacy locations for vaccinations, said in a Sept. 3 announcement that it had updated 2026-2027 COVID-19 vaccines available "for eligible patients based on state regulations" at pharmacies, while its MinuteClinic locations provide "vaccinations for patients beginning at 18 months of age."
COVID-19 vaccines are low- or no-cost with most insurance plans, the company said.
This article originally appeared on USA TODAY: What's going on with COVID? The latest on strains, cases, symptoms.
