A little over 10 million uninsured have gained health care coverage throughout the U.S., either through Medicaid or state and federal exchanges, since the Affordable Care Act (ACA) coverage expansion programs opened for enrollment last year, according to a new report from U.S. Department of Health And Human Services’ (HHS).

According to the report, the uninsured rate among adults ages 18 to 64, as of June 2014, was 15.1 percent, down 5 percent from September 2013.

The percentage of those with health coverage improved most among blacks and Latinos throughout the U.S. The number of uninsured blacks dropped 6.8 percent, as of June 2014, with more than 1.7 million gaining health insurance. The Latino uninsured rate fell 7.7 percent, as more than 2.6 million got coverage. 

The 2014 reduction in the number of uninsured adults builds on earlier effects of the ACA on health insurance coverage. Nearly 950,000 individuals in six states (California, Colorado, Connecticut, Minnesota, New Jersey, and Washington) and the District of Columbia gained coverage before January 1, 2014, from early Medicaid expansions under the Affordable Care Act.

And an estimated 3.1 million young adults gained coverage under a parent’s employer-sponsored or individual market plan under the ACA's expansion of dependent coverage up to age 26, which was effective for plan years beginning on or after September 23, 2010.

In California, the Kaiser Family Foundation estimates that 3.4 million previously uninsured Californians now have gained health care coverage through ACA programs, which include the Medi-Cal expansion and subsidized premiums for Covered California health plans. The Commonwealth Fund estimates that California’s uninsured rate dropped from 22 percent to 11 percent since the exchange opened for business.

The HHS report is based partially on Gallup poll data released last week and backs up July estimates from the New England Journal of Medicine, both of which said the ACA has been a factor in the decline of the country's uninsured rate.