CareFirst BlueCross Blue Shield is the largest health insurer in the Mid-Atlantic region. It is a subsidiary of the Blue Cross and Blue Shield Association. The insurer has 3.2 million members across the District of Columbia, Maryland, and Northern Virginia. CareFirst has the nation's largest Patient-Centered Medical Home (PCMH) program. In this type of program, all patient care is coordinated through a primary care physician to ensure that patients receive necessary medical care and remain informed throughout the care process.