"If they're vaccinated, they are safe. If they are not vaccinated, they are not safe. They should still be wearing a mask or better yet, get vaccinated," she told "This Week" co-anchor Martha Raddatz.
Since the new mask guidance was announced on Thursday, many states, local governments and businesses have updated their mask ordinances based on the CDC's recommendation that vaccinated individuals can be maskless indoors, outdoors or in large crowds. The guidelines still call for masks to be worn on public transportation and in homeless shelters, hospitals and prisons.
Some states, including California, Hawaii, Massachusetts and New York, are keeping their universal mask mandates intact.
Pressed on the challenges in enforcing new mask guidelines, CDC Dir. Walensky says: "This is not permission for widespread removal of masks... these decisions have to be made at the jurisdictional level, at the community level." https://t.co/wbEM2Uitmk pic.twitter.com/gLIkZl1tdt— This Week (@ThisWeekABC) May 16, 2021
As late as Tuesday, Walensky and other health officials were still recommending universal mask wearing during a hearing on Capitol Hill.
"When it was finally announced on Thursday it came as a huge surprise. It left some administration officials, doctors, businesses off guard. So why so suddenly, and why did you not tell the Senate panel what you had decided?" Raddatz asked.
"During the past week we were making decisions," Walensky responded. "Our subject matter experts were working just as I was testifying in front of Congress."
CDC Dir. Rochelle Walensky defends new mask guidance for vaccinated Americans, telling @MarthaRaddatz: "We now have science that has really just evolved even in the last two weeks that demonstrates that these vaccines are safe, they are effective." https://t.co/gpjJwNg0q7 pic.twitter.com/0t0SX6OmXN— This Week (@ThisWeekABC) May 16, 2021
Walensky and other U.S. health officials have stressed that their guidance is up to individuals to follow and if vaccinated people wish to continue wearing their masks they can.
"We wanted to deliver the science of the individual level, but we also understand that these decisions have to be made at the community's level," Walensky said.
The CDC is also facing criticism from some infectious disease specialists who are concerned that there is no way of knowing who is vaccinated -- leaving vulnerable populations, including some children who don't have the option of getting vaccinated, at risk if everyone decides to stop wearing masks.
"The challenge here is that not everybody is eligible for vaccination," Walensky told Raddatz. "We still have children under the age of 11 and they should obviously still be wearing masks. So, if you're unvaccinated, we are saying, wear a mask, continue to distance if you're unvaccinated and practice all of those mitigation strategies."
"Who is supposed to be the vaccination police?" Raddatz pressed. "You look at Costco and Walmart, these essential workers, what are they supposed to do? There again, there's a quarter of the country that says they will not get vaccinated."
"We are asking people to take their health into their own hands to get vaccinated, and if they don't, then they continue to be at risk," she said.
.@martharaddatz: "Who is supposed to be the 'vaccination police'... what are they supposed to do?"— This Week (@ThisWeekABC) May 16, 2021
CDC Dir. Walensky: "We are asking people to take their health into their own hands, to get vaccinated and if they don't they continue to be at risk." https://t.co/wbEM2Uitmk pic.twitter.com/FQKwQFP8UU
Raddatz also asked Walensky what the CDC knows about the "breakthrough" COVID-19 infections in eight vaccinated members of the New York Yankees.
"We're still working to understand what has happened in that," Walensky said. "I would consider that when you look at the details that I'm aware of, seven of those eight were completely asymptomatic. The eighth was a mild case."
"This is the vaccine working," Walensky continued. "You didn't get a severe infection. You didn't require a hospitalization. And most likely, those people were not transmitting to other people."