Though they weren’t targeted to be guinea pigs for the federal government’s new prescription drug program, the most vulnerable of the sick and elderly in this country have become just that.

On Jan. 1, “dual eligibles,” the estimated 6 million Americans who qualify for both Medicare and Medicaid were switched over to a private insurer who contracted with the federal government. Some made the choice for themselves. Those who didn’t were randomly assigned to a plan. Some got their new insurance cards. Some didn’t. Some people didn’t exist after the computerized transition.

As a result, thousands of people have discovered that drugs normally paid for by Medicaid were no longer covered by Part D, as the new drug plan is called. Or, they found out that they now had to come up with a co-pay they couldn’t afford. Some left pharmacies without prescriptions for serious illnesses. Those who have stepped in to try to help have been stymied by red tape, swamped phones and Web sites and general confusion.

Reacting to this debacle, President Bush directed insurers to cover 30-day supplies of drugs for dual eligibles and not charge them more than $5. Some states have declared health emergencies and said they would offer stopgap financial assistance. But the head of the federal Centers for Medicare and Medicaid Services (CMS), Mark McClellan, has told states that he does not have the authority to reimburse them.

It wasn’t supposed to be this way. The new prescription drug plan was designed to be voluntary. The elderly were to evaluate the private plans and decide whether to join up. But dual eligibles had no choice. The responsibility for their bills was being shifted from Medicaid, which is based on financial need, to Medicare, which is based on age. The change thrust millions of ill-equipped people into a world of confusing choices.

The feds have stated that the best way to evaluate plans is to visit medicare.gov and use the calculators. But as health-care experts pointed out long ago, dual eligibles are less likely to have Web access or computer skills. They are more likely to live alone or in a nursing home or in an assisted living facility. Many have mental illnesses that preclude them from making an informed choice.

The Government Accountability Office issued a report predicting many of the shortfalls that have arisen, but the CMS downplayed those concerns, saying it had effective contingency plans.

Clearly, that isn’t the case. The feds need new plans and more aggressive outreach. Not just for dual eligibles, but for all seniors who face the May 15 deadline for signing up for prescription drug coverage.

If the small subset of seniors affected thus far is any indication, the feds have overestimated their ability to deliver on this new program.