US COVID-19 Wastewater Levels Rise as Fall Approaches, Experts Warn of Seasonal Increase
Wastewater monitoring shows COVID-19 levels at a high point nationally, with experts expecting a rise in cases during the upcoming fall respiratory season.
Wastewater testing conducted by Stanford University’s WastewaterSCAN indicated that COVID-19 concentrations reached a “high” category as of Sept. 18, with levels in August 168% higher than in July and doubling each month since June. The CDC’s own wastewater data for the week ending Sept. 12 classified national activity as “low,” though several states—including Texas, California, Washington and Florida—were marked “high” or “very high.”
Dr. Andi L. Shane, chief of pediatric infectious diseases at Children’s Healthcare of Atlanta, said, "We do seem to be seeing a slight decline, but there continues to be week-to-week variation. 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."
The CDC’s latest variant projections for the four weeks ending Aug. 1 identified variant SW.2 as the most common, accounting for 21% of cases, followed by XFG.1.1 at 16%. WastewaterSCAN, however, found the Omicron subvariant XFG in 65% of samples analyzed on Sept. 12, noting its dominance in recent months. Another strain, BA.3.2, dubbed “cicada,” was detected at low levels and has been linked to a severe sore throat.
Clinicians reported that most strains share symptoms such as body aches, chills, congestion, cough, runny nose, fatigue, fever and headache. Dr. Luis Marcos of Stony Brook Medicine added that COVID-19 can also cause gastrointestinal issues like vomiting and diarrhea.
COVID-19 vaccines remain available through pediatric offices, public health departments and retail pharmacies. The CDC currently recommends vaccination for adults 65 and older and for individuals with high-risk conditions, with eligibility for younger or healthier people determined through shared clinical decision-making. Retail pharmacy chain CVS announced that its 2026-2027 vaccines are offered to eligible patients in accordance with state regulations, and its MinuteClinic sites provide vaccinations for children as young as 18 months, typically at low or no cost with most insurance plans.