The Affordable Care Act’s first open enrollment period from Oct. 1 through April 15 saw 10.3 million previously- uninsured Americans get coverage.

The question of how many enrollees were previously uninsured has been a major questions mark since the inaugural registration period closed. The number is higher than the 8 million people enrolled in private insurance plans under the ACA due to the inclusion of Medicaid enrollees in the tally. Of this number, 35% were under age 35.

The New England Journal of Medicine published a study Wednesday looking at insurance trends before and after the enrollment period, and found larger pools of enrollees gained coverage in states that expanded their Medicaid programs. Under the ACA, 26 states and the District of Columbia expanded their programs. 

The report finds the uninsured rate for adults between the ages of 18 and 64 fell to 16.3 % in April 2014 from 21% in September 2013. The 5.2 percentage point change amounts to more than 10 million people, the study finds. The data doesn’t include the 3 million young adults up to age 26 who were eligible to stay on a parent’s insurance plan under the law.

The largest coverage change was for Latinos and blacks ages 18 to 34. Low-income adults in states that expanded Medicaid also experience a 5.1 percentage point change in the number of people covered. Those making up to 400% of the federal poverty level, which was $45,000 for an individual and $94,000 for a family of four this year, were eligible for subsidies to lower the cost of their monthly premiums.

The Department of Health and Human Services reported that 9 in 10 people on the federal exchange received subsidies in the law’s first year, lowering their costs to $69 a month on average.

The ACA mandates every individual in the country have insurance by the end of open enrollment period, or they will face a fine of $95 a year, or 1% of their annual income for failing to comply.

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