An analysis conducted by the California Association of Health Plans—an insurance trade group—concluded that Californians could be left to foot a multibillion-dollar check as the state grapples with how to fund costly new hepatitis-C treatments.

The group forecast that subsidizing pricey new hepatitis-C medications—like Gilead Sciences’ Sovaldi and Harvoni—for patients in prisons, state hospitals and other state programs could cost between $512 million to $5.2 billion. The large gap in the estimate is due to uncertainty surrounding how many patients will receive these treatments and what discounts will be given by manufacturers, the group said.

The California Department of Health Care Services recently set new guidelines describing which patients can receive state-funded HCV treatment for the liver-destroying disease, estimating that 3,000 to 4,000 members will seek treatment next year and that the department will decide who receives the new drugs based on medical necessity, according to Kaiser Health News.