Of the 50 samples that underwent genetic testing to determine which strain of the coronavirus that causes COVID-19 was present, 42, or 84%, were the delta variant, which appears to be more transmissible. Nearly all new COVID-19 cases in Wisconsin involve the delta variant, including among vaccinated people. 

Vaccination remains critical, the researchers said, since the available vaccines against the virus are effective — even against the delta variant — and help prevent new, dangerous cases.

“They’re still working to keep people from becoming infected, though not necessarily as well as they were against earlier types of the virus,” said David O’Connor, a UW School of Medicine and Public Health professor. “As long as the vaccines are keeping people out of the hospitals, I would say they’re working spectacularly well.”

Wisconsin reported 1,180 new COVID-19 cases Wednesday, for a daily average of of 902, the highest since February, when vaccines were scarce.

Some 353 patients were hospitalized with COVID-19 as of Wednesday, including 114 in intensive care. That is well below the peak of 2,277 patients hospitals with the infection in mid-November but nearly five times the recent low of 74 patients hospitalized with the coronavirus on July 6.

Statewide, 52.3% of residents have had at least one dose of vaccine. Among adults, it’s 63.1%, according to the state Department of Health Services. Higher rates are needed for the “herd immunity” that can prevent outbreaks, health officials have said.