The percentage of Latinos who lack health insurance has fallen by more than a third since the Affordable Care Act kicked in this year, according to a new report from The Commonwealth Fund, a health care policy group.

Historically, Latinos have been one of the least-covered groups in the U.S. when it comes to health insurance. Michelle Doty, the lead author of the report, says the low coverage has a lot to do with employment trends.

“For a long time, Latinos have tended to work in jobs that don’t provide health insurance — low wage and small firms,” Doty says.

But now that coverage gap is quickly being filled, Doty says, at least in states that have expanded Medicaid eligibility under the Affordable Care Act. The uninsured rate for Latinos has dropped from 35 percent to 17 percent in less than a year.

That shift translates to fewer emergency room visits and more preventive care for patients at the AltaMed community clinics that Alfonso Vega runs in Southern California. The clinics serve many low-income Latinos, many with diabetes. Without insurance, Vega says, many patients would avoid health care until crisis hit, but that has been changing as more people have enrolled in Medicaid in the last few months.

“There’s countless patients that we’re seeing that are seeing a primary care doctor every 90 days like they’re supposed to — getting all the tests that they’re supposed to have done on a periodic basis,” Vega says.

In the states that have not expanded Medicaid coverage under Obamacare — where more than 20 million Latinos live — their uninsurance rates remain basically unchanged.