National Institutes of Allergy and Infectious Diseases Director Dr. Anthony Fauci went on CNN on Sunday to say that Americans who have been vaccinated for COVID-19 should still wear masks so that they don’t “inadvertently transfer” coronavirus to someone else.

“I do want to ask about the coronavirus restrictions, still in effect even for fully vaccinated Americans, some vaccinated Americans may want to feel like they don’t need to wear masks outdoors around others,” said host Dana Bash. “You have been touting how effective the vaccine is. So what is the scientific reason that it isn’t safe for vaccinated Americans to do those things?”

“The issue is it depends on what you mean by safe and relative risks,” Fauci responded. “Let me explain, Dana. The first thing you have to realize when you get vaccinated, your risk of getting effective dramatically diminishes and is very low. So then the question is, why are there restrictions? There are because, in certain circumstances, one can get vaccinated, have no clinical disease at all but get infected and not even know it and have replication of virus in your nasal pharynx and inadvertently transfer it to someone else who might actually be un-vaccinated and get ill.”

“The other reason for wearing a mask is that there are variants that are circulating, and although they’re unusual, we are seeing breakthrough infections, but we’re also seeing variants that are a bit disturbing,” he added. “Fortunately for us, the 117, which is the variant that was originating in the UK, our vaccines are very effective against them. When people say, why can’t I go? You can travel. Your risk is really very low  the CDC is saying that it depends on what your level of risk that you want to take.”

“The one thing you want to do is be careful that you don’t inadvertently infect someone else or that given the fact that we have 70,000, 60-to-70,000 new infection infections in the community, that is a precarious situation,” he concluded. “That’s the point. So we don’t want people to think that you don’t dramatically diminish your risk when you get vaccinated. You absolutely do. The risk is very low. And people who make decisions about what they want to do and it will be a relative risk. what risk am I willing to take?”