CPT codes for vaccines

Does anyone know why so many vaccines are billed using CPT codes (vs. J-code)?

How about some of the monoclonals like Synagis...I think that has a CPT code also (and no J-code)?

I know that the AMA maintains CPT codes....do they maintain for vaccine administration also?

Thanks, all.

vaccines

CPT codes in Medicine section describe the administration of vaccines. J codes describe the substance administered. Medicare has specific administration codes it uses in place of the CPT codes for administration of specific substances (ex, flu and pneumovax).