"The bottom line is, the vaccine does not make you impervious to infection," Gottlieb said during an appearance. "There are some people who are developing mild and asymptomatic infections even after vaccination."
After acknowledging the delta variant of the coronavirus as "much more transmissible" than the first strain, Gottlieb questioned whether that fact should "translate into general guidance" on mask wearing and vaccine requirements in the United States.
"I don't think that's the case," he said. "I don't think we're going to get enough bang for our buck by telling vaccinated people they have to wear masks at all times to make it worth our while. I think we're further into this delta wave than we're picking up. I think in another two or three weeks we'll be through this."