After the insurance exchanges set up under the Affordable Care Act first went live in late 2013, Lori Lomas started combing the website of Covered California on a hunt for good deals for her clients. Lomas is an agent at Feather Financial, in the Sierra Nevada town of Quincy, Calif.; she's been selling health policies in rural communities for more than 20 years.

But in 2013, she noticed a troubling change that surprised her: For many clients, insurance options decreased.

"I just started running quotes for people," Lomas says, "and began realizing that in [some] zip codes, the only thing that shows up is Anthem [Anthem Blue Cross]."

In addition to Anthem, Blue Shield of California used to sell policies to individuals in every county in the state, according to the Department of Managed Health Care, one of California's two teams of health insurance regulators. But by 2014's open enrollment period, Blue Shield had pulled out of 250 zip codes throughout the state, including four entire counties: Alpine, Monterey, Sutter and Yuba.

The gaps are particularly felt in the top third of the state, where thousands of residents now have only one choice of insurer if they want to buy a health policy on the exchange.

That's in contrast, Lomas says, to other spots, like the San Francisco Bay Area, where she's also been helping clients find policies on the state exchange. "I'd do it for them," she says, "and, wow, there are six insurance companies or seven insurance companies. I think that was when I first realized how, truly, we were getting the shaft up here."

Blue Shield of California declined an interview with NPR. But in a written statement, the company reported that it's not selling in certain areas of California because it could not find enough health providers willing to accept a level of payment that would keep premiums low. According to the statement, the company also is not selling in areas where there is no contracted hospital within 15 miles.

Because of the broad changes in the individual health insurance market under the Affordable Care Act, "there is no accurate apples-to-apples comparison between the individual market in 2013 and the individual market in 2014 and beyond," Blue Shield said, adding that "coverage areas were designed to meet regulatory guidance and with patient access to care in mind."

Blue Shield of California is acting within the law, says Shana Alex Charles, director of health insurance studies at UCLA's Center for Health Policy Research. She says Blue Shield could have offered to pay health care providers more. But, at the same time, she adds, insurance companies can't be forced to operate at a loss.

"There's no public charge that says they have to be in those zip codes," she says. "If they determine that it's not within their company's best interests to remain there and sell their product there, then they won't be there."

That's generally allowed under the federal health law — plans don't have to sell throughout an entire state, for example. Consumer advocates say there is often a lack of doctors in rural areas, and agree that insurers shouldn't sell plans where there isn't a good network. But UCLA's Charles says consumers lose when there are not many insurers to choose from.

"Competition breeds choice," she says, "and people that are competing against each other, work to keep the consumer as happy as possible, so that the consumer will choose them. Competition in the marketplace is a good thing, in that it does keep companies, in some sense, honest."

Two other companies — Assurant Health and Moda Healthare selling health policies in Northern California, but not on the state exchange. So if consumers choose to buy those plans, they can't get the subsidies offered under the federal health law.

Assurant Health says it sells individual policies in every California zip code, and covers out-of-state care. Moda Health just started selling individual policies in California for 2015.

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