An influential federal advisory panel has overwhelmingly rejected a plan to give Pfizer booster shots against COVID-19 to most Americans, but it endorsed the extra shots for those who are 65 or older or run a high risk of severe disease.
 
The twin votes Friday represented a heavy blow to the Biden administration's sweeping effort to shore up nearly all Americans' protection amid the spread of the highly contagious delta variant.
 
The decision was made by a committee of outside experts who advise the Food and Drug Administration.