Asked by host Margaret Brennan on CBS’s “Face the Nation” why the CDC is not instructing Americans to get their booster shots now, Gottlieb said the trend in waning vaccine protection is “unmistakable,” before airing an endorsement for individuals to go out and get their third shot.

“We now see very clear evidence of declining vaccine effectiveness over time. There’s different reasons why that may be the case, but the trend is unmistakable. And this has been apparent since the end of the summer, now it’s very clear,” Gottlieb said.

“Anyone who’s eligible for a booster, and most Americans probably are eligible for a booster at this point, should be going out and seeking it,” he added.

Americans were left confused in September when CDC officials appeared to disagree on who was eligible for a COVID-19 booster shot.