In 2003, according to the Heartland Institute's Merrill Matthews, association group health insurance plans offered affordable health insurance to "some 6 million Americans." Matthews responded to the criticism that said that some associations work too closely with their insurance providers. He said, "You would expect the head of AARP to have a good working relationship with the CEO of Prudential, which sells policies to AARP's seniors."[83]
Generally, group health insurance plans cover the cost of medical office visits for illness and checkups, hospitalization, emergency room services, ambulance transportation, operations, physical therapy, and even prescription drugs, to provide several examples of potentially covered health care services. But, every plan is different and it behooves an employee to become familiar with the details of his or her employer's plan before the benefit is needed.
Private insurers offer a variety of supplemental coverages in both the group and individual markets. These are not designed to provide the primary source of medical or disability protection for an individual, but can assist with unexpected expenses and provide additional peace of mind for insureds. Supplemental coverages include Medicare supplement insurance, hospital indemnity insurance, dental insurance, vision insurance, accidental death and dismemberment insurance and specified disease insurance.[19]
The blurring of distinctions between the different types of health care coverage can be seen in the history of the industry's trade associations. The two primary HMO trade associations were the Group Health Association of America and the American Managed Care and Review Association. After merging, they were known as American Association of Health Plans (AAHP). The primary trade association for commercial health insurers was the Health Insurance Association of America (HIAA). These two have now merged, and are known as America's Health Insurance Plans (AHIP).
States regulate small group premium rates, typically by placing limits on the premium variation allowable between groups (rate bands). Insurers price to recover their costs over their entire book of small group business while abiding by state rating rules.[74] Over time, the effect of initial underwriting "wears off" as the cost of a group regresses towards the mean. Recent claim experience—whether better or worse than average—is a strong predictor of future costs in the near term. But the average health status of a particular small employer group tends to regress over time towards that of an average group.[75] The process used to price small group coverage changes when a state enacts small group reform laws.[76]
The term managed care is used to describe a variety of techniques intended to reduce the cost of health benefits and improve the quality of care. It is also used to describe organizations that use these techniques ("managed care organization").[96] Many of these techniques were pioneered by HMOs, but they are now used in a wide variety of private health insurance programs. Through the 1990s, managed care grew from about 25% US employees with employer-sponsored coverage to the vast majority.[97]

Public insurance cover increased from 2000–2010 in part because of an aging population and an economic downturn in the latter part of the decade. Funding for Medicaid and CHIP expanded significantly under the 2010 health reform bill.[9] The proportion of individuals covered by Medicaid increased from 10.5% in 2000 to 14.5% in 2010 and 20% in 2015. The proportion covered by Medicare increased from 13.5% in 2000 to 15.9% in 2010, then decreased to 14% in 2015.[3][10]