More than a million people in three of the poorest U.S. states have had the fabric of their lives torn apart by Hurricane Katrina. Displaced from their homes, many are living in other parts of Louisiana and Mississippi, while others are dispersed across the country in the largest involuntary migration of Americans since the Dust Bowl in the 1930s. The public health infrastructure they depended on in the disaster areas has been destroyed, leaving the displaced without care, coverage or medical records.

The health care crisis resulting from this devastation needs immediate attention. The initial federal response has included establishing and staffing emergency medical shelters in the region. But three weeks have passed since Katrina struck, and the magnitude of the damage requires a broad-scale national plan. We must address the significant physical and mental health needs of the survivors. As Surgeon General Richard Carmona has said: "These public health needs are going to be very, very large, and they are going to go on for some time."

The states hit by Katrina already had among the highest rates of poverty and lowest rates of insurance; nearly one in five in each state lived in poverty, and an equal number lacked health insurance. As survey results published in The Post last Friday reveal, New Orleans evacuees living in Houston shelters were in desperate shape even before Katrina: six in 10 had annual incomes of less than $20,000; over half had no health insurance; four in 10 suffered from disabling or chronic illnesses such as heart disease, diabetes or high blood pressure; and 43 percent were taking prescription medications. Two-thirds relied on hospitals and clinics as their primary source of care; of those, 54 percent used the now destroyed Charity Hospital of New Orleans.

Katrina added thousands more to the ranks of the poor and uninsured. The psychological stress and trauma of the past three weeks will lead to increased demand for mental health services. Many evacuees are newly impoverished and have chronic health care needs that will place additional, costly demands on the care systems in the areas to which they have located. Some 400,000 jobs have been lost; many who are out of work have lost not only their source of income but also their health insurance. Hospitals, clinics, nursing homes, pharmacies and other facilities have been damaged or destroyed. Underserved populations that already had substantial health disparities are now at risk of falling even further behind the rest of America.

A national response to this health crisis is weeks overdue. The administration has taken preliminary steps to respond to the health needs of Katrina survivors, but its approach to addressing the dire need for health coverage has been to negotiate state-by-state waivers to modify Medicaid, the nation's health care safety-net program for the poor. The first such agreement has already been struck with Texas.

Medicaid is the right solution, but this is not the time for business-as-usual waivers of regulations, which are usually granted to offer opportunities for states to innovate. They cannot provide what is needed now by the states and the survivors: a simple and certain solution. This is a situation that calls for a comprehensive and immediate national plan targeted to Katrina survivors -- one that is 100 percent federally financed. The economies of Louisiana, Mississippi and Alabama have been devastated. These states will not have the revenue needed to pay their normal share of Medicaid or to handle additional expenses as they try to rebuild. Likewise, the many states that have accepted Katrina survivors should not have to absorb additional costs.

The president should work with Congress to make Katrina's many low-income survivors eligible for guaranteed 100 percent federally funded Medicaid regardless of where they live today or where they move tomorrow. This should be done even for those who don't fit into one of Medicaid's current eligibility groups and regardless of whether they were previously on Medicaid or were insured.

The goal should be to provide immediate access to health care services, pay providers and avoid creating a new layer of bureaucracy. The payment should be equal, not separately negotiated agreements between each state and the federal government. The bipartisan Emergency Health Care Relief Act, introduced in the Senate last week and endorsed by Majority Leader Bill Frist and Minority Leader Harry Reid, is a good first step toward this goal, but it needs to be simplified and made more comprehensive. In essence, the response needs to be built around three principles: 100 percent federal financing for the health needs of Katrina survivors; health coverage for all survivors, regardless of whether they meet Medicaid's eligibility rules; and a period of assistance tied to the time needed for a full recovery, not set by an arbitrary limit.

As Katrina survivors embark on the road to recovery, they deserve the support of our entire country. The health response that we provide is a measure of our strength and compassion as a nation.

The writer was secretary of health and human services from 1993 to 2001. She is now president of the University of Miami.