About 16.4 million uninsured adults have gained health coverage through the Affordable Care Act’s health insurance marketplaces and provision allowing young adults to remain on a parents plan until age 26, according to an analysis released today by the Department of Health and Human Services. Based on data through March 4 from the Gallup-Healthways Well-Being Index survey, HHS estimates the young adult provision covered about 2.3 million people and the marketplaces the rest. The report includes estimates of coverage gains since the start of the first marketplace open enrollment period in October 2013 by race and ethnicity, household income and state Medicaid expansion status.