National Institute of Allergy and Infectious Diseases head Dr. Anthony Fauci said Sunday on ABC’s “This Week” that Americans who have been vaccinated need to continue wearing masks to protect others from spreading coronavirus.

Anchor George Stephanopoulos said, “We don’t know a lot about how vaccines affect transmission, whether they truly prevent transmission. For people who have been vaccinated, what can they do?”

Fauci said, “Well, you should still be careful, George, that you could conceivably have, because the endpoint of the vaccine efficacy trial is preventing symptomatic disease, which means that potentially theoretically, and maybe, in reality, you’re going to have infection that you don’t get any clinical manifestation, you could be protected from disease and still have the virus, and if that’s the case that’s the reason why you hear all the public health officials say, wear a mask. The reason is, essentially, to protect other people, you may inadvertently infect someone else even though you’re protected. That’s the reason.”

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