Fewer Americans age 60 to 74 should receive the shots, the agency concluded, citing reduced risks and a possible neurological side effect.
In an unusual move, federal health officials narrowed their recommendations for who should receive the vaccine against the respiratory syncytial virus.
The Centers for Disease Control and Prevention advised last year that adults age 60 or older could receive a single lifetime dose of an R.S.V. vaccine, in consultation with their health care providers.
On Wednesday, scientific advisers to the agency reframed that guideline. Based on recent safety and effectiveness data, they unanimously recommended that all Americans age 75 and older receive one dose of an R.S.V. vaccine.
But for adults 60 to 74 years of age, the panel endorsed vaccination only for those with certain serious conditions, such as chronic heart or lung disease, advanced kidney disease and diabetes with organ damage.
The advisers voted not to recommend the vaccine for other adults in this age group, although individuals may still consult with their health care providers to evaluate the risk the infection poses to them.
The C.D.C.’s director, Dr. Mandy Cohen, accepted the panel’s recommendations on Wednesday afternoon.