Every county in both Florida and Arkansas currently has high levels of community transmission, according to July 18-24 data from the CDC.
The agency considers a county to have high transmission if there are 100 or more COVID-19 cases per 100,000 residents or a test positivity rate of 10 percent or higher in the last seven days. As of July 24, almost 44 percent of the nation's counties fell into this category.
Several other states — Missouri, Louisiana, Mississippi and Alabama — have high transmission in nearly every county.
Over the last week, COVID-19 cases in Florida accounted for almost a quarter of all U.S. cases, more than any other state. Florida's average number of new daily infections is more than triple its daily average from two weeks prior, according to data from Baltimore-based Johns Hopkins University.
"We could be an entire hospital full of COVID in a matter of a month if things don't begin to slow down or vaccinations don't increase," Chad Neilsen, director of infection prevention at the University of Florida Health Jacksonville, told CNN last week.
Arkansas Gov. Asa Hutchinson said COVID-19 is surging because of the state's low vaccination rate, according to CNN. About 36 percent of Arkansas residents are fully vaccinated, according to the most recent Johns Hopkins data.
However, Mr. Hutchinson said there's been a 40 percent rise in vaccinations since he began holding meetings promoting vaccination.
"We're seeing people that were previously resistant or hesitant about it coming in and getting the vaccination," Mr. Hutchinson told CNN.