As of May 1, 2014, an estimated 20 million Americans have gained health care coverage under the Affordable Care Act through its insurance exchanges and other coverage provisions, according to a Commonwealth Fund health policy report published in the New England Journal of Medicine.

Health Care Coverage Under the Affordable Care Act – A Progress Report states that eight million people purchased coverage through the individual marketplaces before the ACA’s first open enrollment period closed March 31. Millions more gained coverage through Medicaid and CHIP, purchased coverage directly from insurers, and gained coverage from an ACA provision allowing young adults to stay on their parents’ plans until age 26. The report notes that experience with the ACA will vary among states and may have the paradoxical effect of increasing disparities across regions.

The authors also warn that the sustainability of the ACA health care coverage expansion will depend largely on controlling the costs of care to prevent premiums from becoming unaffordable. The next great challenge facing health care reform is to develop and spread innovative approaches to health care delivery that provide greater quality at lower cost.