Since the ACA, Fewer Adults Are Uninsured, but More Are Underinsured “Compared to 2010, when the ACA became law, fewer people today are uninsured, but more people are underinsured. Of the 194 million U.S. adults ages 19 to 64 in 2018, an estimated 87 million, or 45 percent, were inadequately insured (see Tables 1 and 2). […]