James K. Flynn has written:

'Fiscal policy implications of the 1988 Medicare Catastrophic Coverage Act'

There are four stages in Medicare coverage. The third stage lies between the second and the catastrophic coverage (fourth stage) prescription drug program. A person is responsible for a much higher cost of prescription drugs until they reach the catastrophic (fourth) coverage threshold. This third stage is called the doughnut hole. It is slowly being filled and will finally be covered.

part a is hospital coverage, part b is dr coverage

Typically Medicare does not have this type of coverage under its policy. You should find out more information about this from your local Medicare provider.

Medicare