Some key provisions take affect at midnight, CBS News Correspondent Sharyl Attkisson reports.
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Millions of seniors are about to get their first taste of health care reform, and a lot of them will probably like it.
For the first time, the 45 million seniors on Medicare can get free annual physicals. No more co-payments. They'll get free screenings for diabetes and cancer. That includes mammograms and colonoscopies.
"We think it will make the lives and wellness of seniors much better, and in the end it will help drag down costs as diseases are caught sooner before they become more costly to treat," said James Chiong, executive director of the Health Information Campaign.
Another plus: shrinking the so-called doughnut hole. Medicare patients used to have to pay the entire cost of their prescriptions after they spent $2,830 until expenses reached $6,440. Now, they'll get a 50 percent discount on certain brand name drugs and pay 7 percent less on generics.
There are also less popular provisions. Medicare patients earning more than $85,000 as individuals and $170,000 as couples will pay higher premiums for prescription drugs. Non-prescription drugs like cold and allergy medicines can't be reimbursed through tax-free flexible spending or health savings accounts.
However, the biggest worry could be something else entirely.
"I think there's a very real concern about having adequate numbers of Medicare doctors," said Dr. Herbert Pardes, president and CEO of NewYork-Presbyterian Hospital and NewYork-Presbyterian Healthcare System.
That could mean long waits to see the doctor.
"I think they will see delays in the timing of their appointments," said Pardes. "I think a number of doctors who have been frustrated because of the Medicare fee level will actually stop taking Medicare, so that's a real worry for all of us."
Republicans have promised to do what they can to stop or roll back health care reform, but advocates say most of these first provisions taking effect are quite popular and will be hard for anyone to take away.