More than 543,000 people selected a health plan through the federally-facilitated Health Insurance Marketplace during the first week of open enrollment, the Centers for Medicare & Medicaid Services announced today. Two-thirds of the plan selections were by 2015 enrollees who were actively or automatically renewing coverage or selecting a new plan for 2016; the rest did not have current Marketplace coverage. Open enrollment for coverage beginning in 2016 runs through Jan. 31. CMS plans to issue weekly estimates of plan selections and renewals during the open enrollment period.