"Another chunk of those people who are remaining uninsured have been uninsured for a long period of time and therefore may be harder to reach, a harder group to bring into the fold," said Bianca DiJulio, associate director with the foundation's Public Opinion and Survey Research Program.
The largest share of the newly insured -- 34 percent -- are covered in the Medi-Cal, the state's version of Medicaid. Fourteen percent say they are insured through their employer and 12 percent purchased insurance through Covered California, the marketplace established under the ACA.
The newly insured largely say their health care needs are being met with 86 percent saying their needs are being "very well" or "somewhat" well met, up from 51 percent in 2013.
Before the health law, nearly 6 million adults in Californians were uninsured, the most of any state, and Latinos made up more than half of them. While initial campaigns to reach Latinos were widely criticized, newer efforts seem to be more successful. The survey found that whites and Latinos signed up in nearly equal proportions, 79 percent for whites and 74 percent for Latinos (after excluding those Latinos who would be ineligible for ACA benefits due to their immigration status).
Yet last year's survey of the previously uninsured after the first open enrollment concluded showed that whites and Latinos signed up at the same rate, 61 percent.
Advocate de Guia said the small gap found this year -- five percentage points -- was worrisome, because grants to community groups to help people sign up have declined by millions of dollars. "Enrollment dollars are going down or being cut," she said. "We don't want to see that gap widen over time."
Gerald Kominski, director of the UCLA Center for Health Policy Research said the survey findings were "obviously very good news," but cautioned that the findings have a limitation. The group of people that is being followed all had previously lacked insurance.
"There's another cohort of Californians who are not in this survey -- people who had insurance and lost it," he said in an interview. "Some portion of those individuals remain uninsured."
Overall, those saying it's hard to afford health care dropped from 86 percent in 2013 to 49 percent today.
In the survey, 85 percent of the uninsured say paying for health care is their top financial concern -- ahead of paying their mortgage or rent. Of those who have gained coverage, paying for health care now ranks fourth among financial concerns -- behind rent/mortgage, utilities and even gasoline.
"It's below the price of gas," said UCLA's Kominski. "I found that truly remarkable ... the fact that health care for people newly insured (is) no longer a primary concern, I think is significant."
While 76 percent of the newly insured say their experience with their plan has been positive, some are reporting issues in accessing care, including 28 percent who say they had to wait longer than they thought they should have to for an appointment or finding that a doctor said they would not accept their insurance (17 percent of Medi-Cal recipients; 23 percent of people with a Covered California plan).
This survey is the third in a series of people who were uninsured in 2013, before the Affordable Care Act went into full effect. From February 18 to May 13, 2015, 1,105 adults who had participated in the first survey were contacted. The margin of sampling error is plus or minus 4 percentage points for results based on the full sample, 5 percentage points for recently insured Californians, and 8 percentage points for those Californians who remain uninsured.