It’s been six years since the passage of the Affordable Care Act and the nation’s uninsured rate has dropped to a record low. That’s the good news.

On the other hand, a cornerstone of the ACA — the health insurance marketplaces — are facing some real challenges in reaching some of the nation’s most vulnerable populations, according to presenters at a Monday morning Annual Meeting session on “Insuring the Right to Health — Enrolling Underserved Populations through Health Insurance Exchanges.” Presenter Mary Pittman, president and CEO of the Public Health Institute, said the big questions facing the ACA today are how states address continuing barriers to insurance enrollment as well as ensure that affordable insurance is available to all.

Currently, she noted, about 10 percent of the country is still without insurance, with southern states home to the most uninsured residents. A number of reasons may be holding people back from signing up: Their state didn’t expand Medicaid eligibility, they’re simply unaware of the insurance marketplace, they’re ineligible for marketplace subsidies or they need help navigating the enrollment process. Still, thanks to the ACA, about 20 million people had gained insurance as of 2016, with nearly 13 million enrolling through insurance marketplaces, said session speaker Nadia Siddiqui, director of Health Equity Programs at the Texas Health Institute.

Siddiqui described the evolution of marketplace activities to reach vulnerable and under-served populations. For example, in 2013, she said, the focus was mainly on getting the online marketplaces up and running, while in 2014, reaching out to new populations and retaining hard-to-reach populations in the marketplace gained a lot more attention. Now, she said the challenge is retaining those hard-to-reach consumers in the face of declining outreach resources and funds.

She also reported that insurance marketplaces that made real headway in reaching communities of color were those that “made it a mission to advance health equity.” In 2013, Siddiqui said, seven state marketplaces made explicit efforts to reach diverse communities — “it really was about integrating the equity focus across planning and design,” she said.

For example, during the second marketplace open enrollment period, there was a proliferation of appropriately translated materials, with many more targeted strategies designed to pinpoint ZIP codes with high numbers of uninsured residents. In Houston, for instance, officials viewed the uninsured rate as a “public health crisis” and actually activated the city’s incident command structure, which is typically used in outbreaks and disasters, to reach vulnerable residents.

To measure how the marketplaces are contributing to health equity, the Texas Health Institute developed the Marketplace Health Equity Assessment Tool (M-HEAT). The tool, which has been tested in Connecticut and California, examines elements such organizational commitment, planning management, community engagement and collaboration, navigator assistance and marketing and outreach.

Session presenter Colleen Stevens, director of marketing for Covered California, the state’s insurance marketplace, said enrollment messages need to resonate with people on an emotional level.

From the very beginning, she told attendees, Covered California has been committed to reaching Hispanic communities. However, in the early days of enrollment, officials began hearing rumors that Hispanic residents weren’t signing up. So, Stevens and her colleagues went to the marketplace call center and asked Spanish-speaking operators what they were hearing. It turned out that Hispanic residents feared the enrollment process would put them at risk for immigration questions and possible deportation. In response, Stevens said, Covered California produced a fact sheet to reassure consumers that their information remains confidential.

Fortunately, their enrollment efforts have paid off: The uninsured rate in California has been cut in half — the largest decrease in the nation.

“If you think (enrollment) is just going to happen naturally,” Stevens said, “you’re never going to be successful.”

Here in Colorado, Michele Lueck, president of the Colorado Health Institute, described the state as “all in” — meaning Colorado expanded Medicaid eligibility, set up its own stated-based insurance marketplace, tried offering a health insurance co-op (though it folded) and took part in the Centers for Medicare and Medicaid’s Innovation Center to test creative payment and service delivery models.

To date, Lueck told session attendees, Colorado has experienced a dramatic decrease in uninsured residents, from about 15 percent in 2013 to about 6 percent in 2015. But while officials predicted most newly insured residents would get coverage via the marketplace, many more got coverage through the expanded Medicaid program.

“What we got really wrong was how people would get insurance,” she said.

Now, Lueck said, the question is whether the state-based marketplaces can maintain their independence and create a sustainable path forward.

“The jury,” she said, “is still very much out.”