What act mandates that insurers must guarantee issue health plans to individuals who lose prior group health coverage?

The correct choice is the Health Insurance Portability and Accountability Act (HIPAA). HIPAA includes provisions that protect health insurance coverage for workers and their families when they change or lose their jobs. One of its significant roles is ensuring that individuals who lose their prior group health coverage have guaranteed access to health insurance coverage, preventing them from being denied coverage due to pre-existing conditions. This protection is crucial for maintaining continuity of care and access to necessary medical services, which is especially important during transitions leading to potential health risks.

The other options mentioned do not specifically address the guarantee of issue health plans in the context described. COBRA deals primarily with the continuation of health insurance coverage for individuals who lose their jobs, allowing them to keep their existing coverage for a limited time. The Medicare Modernization Act focuses mainly on enhancing Medicare coverage and prescription drug benefits but does not mandate guaranteed issue health plans for those losing group coverage. The Affordable Care Act also provides important protections regarding pre-existing conditions and ensures access to insurance, but the specific requirement to guarantee issue health plans for individuals losing prior group coverage stems from HIPAA provisions.