What is a prepaid health plan under which a member pays a monthly premium in exchange for comprehinsive care?

A Health Maintenance Organization (HMO) would fit this definition.

In exhange for a monthly fee, the member is entitled to a range of medical services on an as-needed basis. An HMO typically emphasizes preventative care, althought acute care is certainly available.

HMOs are similar to insurers in that they are risk-bearing entities. That is, members pay the equivalent of premiums as a condition of membership. Therefore, insurance regulators regulate HMOs to ensure that they remain financially sound and can provide services pursuant to the membership contracts