Tens of thousands of Georgia Medicaid beneficiaries are set to switch health plans beginning Saturday in an unprecedented shift in enrollment for the government program. Today marks the planned move of more than 200,000 enrollees to an Ohio-based “care management organization,” or CMO, CareSource. Under a new state contract, taking effect Saturday, the insurer joins three other CMOs delivering care to 1.3 million Georgians, most of them children.