Evidence for vaccine booster shots isn't clear, but Biden moves ahead anyway

The U.S. is poised to begin rolling out booster shots in a matter of weeks, with still one major sticking point to resolve: It's not entirely clear yet that third shots are needed.

President Joe Biden recently vowed to begin deploying boosters the week of Sept. 20, pending a green light from federal regulators.

But health experts advising the government on that decision say the August announcement by Biden's political appointees came as somewhat of a surprise. It also was unclear, they said, why that date was chosen at all.

Evidence for boosters is still mixed, and announcing a timetable -- while likely popular with much of the public -- put independent government regulators in a corner by suggesting they would sign off no matter what.

"That doesn't mean you can't get out (of the decision), but I think the public expectation is that boosters are needed now," said Dr. Henry Bernstein, a pediatrician at Northwell Health Cohen's Children Medical Center in New York who has advised the Centers for Disease Control and Prevention on vaccines.

"There's a lot more data to be reviewed and work to be done in evaluating whether boosters are needed in various populations," Bernstein added.

The question of whether America's immunity is waning has become an urgent question in recent months with the rise of the delta variant and large pockets of the country still unvaccinated.