Still, private insurance remained unaffordable or simply unavailable to many, including the poor, the unemployed, and the elderly. Before 1965, only half of seniors had health care coverage, and they paid three times as much as younger adults, while having lower incomes. Consequently, interest persisted in creating public health insurance for those left out of the private marketplace.
In the United States, Medicare is a federal social insurance program that provides health insurance to people over the age of 65, individuals who become totally and permanently disabled, end stage renal disease (ESRD) patients, and people with ALS. Recent research has found that the health trends of previously uninsured adults, especially those with chronic health problems, improves once they enter the Medicare program. Traditional Medicare requires considerable cost-sharing, but ninety percent of Medicare enrollees have some kind of supplemental insurance—either employer-sponsored or retiree coverage, Medicaid, or a private Medigap plan—that covers some or all of their cost-sharing. With supplemental insurance, Medicare ensures that its enrollees have predictable, affordable health care costs regardless of unforeseen illness or injury.
On the 1st of August, 2018 the DHHS issued a final rule which made federal changes to Short-Term, Limited-Duration Health Insurance (STLDI) which lengthened the maximum contract term to 364 days and renewal for up to 36 months. This new rule, in combination with the expiration of the penalty for the Individual Mandate of the Affordable Care Act, has been the subject of independent analysis.
Historically, health insurance has been regulated by the states, consistent with the McCarran-Ferguson Act. Details for what health insurance could be sold were up to the states, with a variety of laws and regulations. Model acts and regulations promulgated by the National Association of Insurance Commissioners (NAIC) provide some degree of uniformity state to state. These models do not have the force of law and have no effect unless they are adopted by a state. They are, however, used as guides by most states, and some states adopt them with little or no change.
Health insurance primarily protects individuals from the prohibitively high costs of surgical procedures, inpatient hospital care, and emergency attention. Though health insurance itself can become costly for a family, it is only a small fraction of the potential costs associated with unforeseen illnesses and emergencies (for example, the diagnosis and treatment of cancer or a heart attack).
President Harry S. Truman proposed a system of public health insurance in his November 19, 1945, address. He envisioned a national system that would be open to all Americans, but would remain optional. Participants would pay monthly fees into the plan, which would cover the cost of any and all medical expenses that arose in a time of need. The government would pay for the cost of services rendered by any doctor who chose to join the program. In addition, the insurance plan would give cash to the policy holder to replace wages lost because of illness or injury. The proposal was quite popular with the public, but it was fiercely opposed by the Chamber of Commerce, the American Hospital Association, and the AMA, which denounced it as "socialism".
A 2011 study found that there were 2.1 million hospital stays for uninsured patients, accounting for 4.4% ($17.1 billion) of total aggregate inpatient hospital costs in the United States. The costs of treating the uninsured must often be absorbed by providers as charity care, passed on to the insured via cost-shifting and higher health insurance premiums, or paid by taxpayers through higher taxes.