Fauci says Johnson & Johnson one-shot vaccine should have been two all along

The single-dose Johnson & Johnson vaccine that last week won approval from FDA advisers for a booster shot probably should have been a two-shot vaccine from the start, the nation's top infectious disease physician said Sunday. 

"What the advisers to the FDA felt is that, given the data that they saw, very likely this should have been a two-dose vaccine to begin with," Dr. Anthony Fauci told ABC's "This Week."

The Food and Drug Administration vaccine advisory panel unanimously approved booster shots for the vaccine Friday for all J&J recipients 18 years and older – as early as two months after the first dose.

The panel's recommendations for the Moderna and Pfizer boosters were for Americans 65 and older or in higher risk groups.