The board of California's health insurance exchange, Covered California, on Thursday decided not to allow insurance plans that do not meet Obamacare standards to continue operating in that state, according to the agency's official Twitter account. The move effectively rejects the fix President Barack Obama proposed to salve the deeply troubled rollout of the Affordable Care Act.
That state already faces an age-old health insurance challenge: The old folks are outrunning the kids in the race to sign up for California's insurance. If the trend continues, it might lead to higher premiums down the line.
People between the ages of 45 and 64 have enrolled in California's health exchange at a much higher rate than their overall portion of the state's total population, while younger adults' enrollment levels essentially track their overall population size, data released on Thursday revealed.
If the trend holds up, it could mean that insurance plans are overweighted with older customers, and underweighted with younger, presumably healthier people. Since their premiums are much needed to offset the cost of benefits paid out to sicker individuals, that could lead to higher premium prices in 2015.
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California's enrollment numbers are being closely watched because of its huge population, and because the state is running its own Obamacare exchange. Thirty-six other states are letting the federal government sign up their residents through HealthCare.gov.
As of Monday, 79,891 people had so far signed up for insurance through the Covered California exchange. Thursday was the first time The Golden State released a breakdown of who was enrolling, and the initial picture shows a lot more gray hair than surfer blonde.
For example, 10,387 people between the ages of 55 and 64 enrolled in Obamacare insurance in California in October, which was a whopping 34 percent of all individuals enrolled in that month. But that age group comprises just 11 percent of the state's overall population.
In second place, 22 percent of the total number of individuals enrolled were adults between the ages of 45 and 54, who only represent 14 percent of the state's total population.
In stark contrast, there were just 2,344 people between the ages of 18 and 25 enrolled in October, which was 8 percent of total individual enrollment. That age group makes up 7 percent of the state's population.
The 26- to 34-year-old age group comprised 15 percent of total enrollment, with 4,580 people signed up; they comprise 14 percent of the state's population.
And 35- to 44-year-olds made up 16 percent of Covered California's individual enrollment, with 4,937 signed up. That group makes up another 14 percent of the total state population.
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The number of total enrollments among all people as of Oct. 31 was greatly exceeded by the total number of people who had filled out applications for enrollment, which was 114,512 as of that date.
Covered California said the rate of applications for younger adults, again, closely tracked their overall population in the state, while older adults were overrepresented compared with their population. But the difference among the age groups in applications was not as dramatic as in enrollments.
In a statement, Covered California pointed out that about 22.5 percent of people who enrolled in October were between ages 18 and 34.
Peter Lee, the health exchange's executive director, called the state's overall enrollment "strong," and said the fact that young adults were signing up at a rate consistent with their presence in the population was a good thing.
"Enrollment in key demographics like the so-called young invincibles is very encouraging," Lee said.
"The enrollment numbers so far reflect a tremendous demand for health insurance, which will only grow stronger as the facts about Covered California health coverage options spread across California's diverse communities of language and culture."
Covered California officials said that about 30 percent of the people who had submitted applications for insurance as of Oct. 31 were deemed eligible for subsidies to offset the cost of that coverage because their household incomes fell below 400 percent of the federal poverty level. Another 31 percent were deemed ineligible for subsidies.
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A total of 39 percent of those who submitted applications are possibly eligible for California's Medicaid program, Medi-Cal, which covers lower-income people. California is one of 26 states that is expanding its Medicaid program to cover many people who were previously ineligible due to their low incomes.
As of Nov. 19, a total of 360,464 people had completed applications on Covered California's exchange. The rate of applications completed has spiked up considerably from October, when the highest single week saw 47,054 applications completed. In the first week of November, there were 69,236 applications, which increased to 71,188 in the second week.
—By CNBC's Dan Mangan. Follow him on Twitter @_DanMangan