"We are yet at another pivotal moment in this pandemic, with cases rising again and some hospitals reaching their capacity in some areas," said Walensky.
The CDC has not revised its masking guidance, even as the Delta variant continues to sweep the United States, driving up case counts. Walensky declined to say if the CDC is considering changing the guidance.
"Unvaccinated individuals account for virtually all 97% of the COVID hospitalizations and deaths in the U.S.," said White House COVID-19 response coordinator Jeff Zients at the same briefing.
Zients also said Florida, Texas and Missouri - three states he said have lower vaccination rates - accounted for 40% of all cases nationwide.
"For the second week in a row, 1 in five new cases have occurred in Florida alone," he added.