"The Delta virus is much more infectious. Its viral load is thousands of times higher than our previous variants. It's going to make even the average healthy person sick now," said Dr. Catherine O'Neal of Our Lady of the Lake Regional Medical Center in Baton Rouge, Louisiana.
Just three states now account for 40% of new COVID cases, but cases are rising elsewhere too.
"We do know that in our ICUs, we are seeing younger people intubated who are very sick or who are on the floors and are very sick. That should be a gigantic wake-up call," said Jeanne Marrazzo, director of the Division of Infectious Diseases, at the University of Alabama at Birmingham
Although unvaccinated Americans are driving the surge, more vaccinated Americans are testing positive and possibly transmitting the virus.
Even the White House has seen new breakthrough cases. Now the Biden administration is talking with the CDC about whether masking guidelines should be updated.
"We've never said that battle is over, it's still ongoing. It would more concerning -- or should be more concerning -- to you and the American people if we were not having those conversations," White House Press Secretary Jen Psaki said Thursday.
DC guidance currently says vaccinated Americans can resume normal activities without wearing a mask or socially distancing.
The problem though — without mask mandates, unvaccinated Americans are also dropping their masks. Health officials fear the honor system is failing in many places.
"We are always looking at the data as the data come in. Our guidance has been clear since, since we put it out several months ago," CDC Director Dr. Rochelle Walensky said Thursday.
The CDC says its guidance remains unchanged, but some vaccinated health experts say they are keeping their masks on.
"I have not really taken my mask off. I go outside and walk — I still have my mask. I certainly, when I go into the post office or the grocery store or the pharmacy or any other place, I keep my mask on. It's added protection," Dr. Zeke Emanuel told CNN.