WASHINGTON (AP) — The National Institutes of Health director says a government advisory panel’s decision to limit Pfizer COVID-19 booster shots to Americans 65 and older as well as those at high risk of severe disease is a preliminary step and predicts broader approval for most Americans “in the next few weeks.”

Dr. Francis Collins told “Fox News Sunday” that the panel’s recommendation Friday was correct based on a “snapshot” of available data on the effectiveness of Pfizer’s two-shot regimen over time. But he said real-time data from the U.S. and Israel continue to come in showing waning efficacy among broader groups of people that will need to be addressed soon.

Collins, who also appeared on CBS’ “Face the Nation,” said: “I think there will be a decision in the coming weeks to extend boosters beyond the list that they approved on Friday.”

Dr. Anthony Fauci, who is President Joe Biden’s chief medical adviser, on Sunday praised the advisory board’s plan for covering a “good chunk” of Americans. But he stressed that “this is not the end of the story” based on evolving data and said the recommendations will likely be expanded in the coming weeks to months.

The Food and Drug Administration will consider the advisory group’s advice and make its own decision, probably within days. The Centers for Disease Control and Prevention also is set to weigh in this week.