More than 5 million uninsured young U.S. adults ages 19-34 are eligible for Medicaid or will become eligible for Medicaid in January, a non-profit says.

The report, prepared by researchers at the Urban Institute, with support from the Robert Wood Johnson Foundation, said this group of young adults, dubbed "young invincibles," live in states that opted to expand Medicaid coverage to individuals with incomes up to 138 percent of the federal poverty level.

Many of these young uninsured-but-eligible for Medicaid adults have a prior or ongoing relationship with existing social programs -- unemployment assistance, a child getting food from the Supplemental Nutrition Assistance Program or Medicaid benefits for uninsured children.

The study also underscored the young adults eligible for Medicaid are not a homogenous group. About 1-in-5 of the uninsured young adults who will be eligible for Medicaid are students; 42 percent work; and 18 percent are unemployed.

"Just because people in their 20s and early 30s are sometimes referred to as 'young invincibles' does not mean that they are immune from disease or accidents or needing routine health services," Katherine Hempstead of the Robert Wood Johnson Foundation said in a statement. "Reaching these young adults to make sure they understand their options for free or low-cost health insurance is a critical first step in helping them get the healthcare they need." Topics: Robert Wood