Nearly 17 million Americans have gained health insurance since key provisions of the Affordable Care Act were implemented in 2013, according to a study by nonprofit research organization RAND Corp. The report, released Wednesday, May 6, in the journal Health Affairs, found that from September 2013 to February 2013, 22.8 million individuals signed up for coverage, while 5.9 million lost coverage, resulting in a net gain of 16.9 million.