Part D: Prescription Drug Plans How does Medicare drug coverage work? Helps cover the cost of prescription drugs (including many recommended shots or vaccines) Plans that offer Medicare drug coverage are run by private insurance companies that follow rules set by Medicare Cover specific brand name and generic drugs that are included in the drug list, known as the formulary There are 2 ways to get Medicare drug coverage: Medicare drug plans - these plans add Medicare drug coverage to Original Medicare, some Medicare Cost Plans, some Medicare Advantage Private Fee - for - Service Plans, and Medical Savings Account (MSA) Plans. You must have Part A and/or Part B to join a separate Medicare drug plan Medicare Advantage Plans or other Medicare health plans with drug coverage. You get Part A, Part B, and Medicare drug coverage through these plans. You must have Part A and B to join a Medicare Advantage Plan, and not all Medicare Advantage Plans offer drug coverage