Medicare’s Part D prescription drug program spent nearly $4.6 billion in the first half of 2015 on new hepatitis C virus (HCV) treatments—a cost that amounts to nearly as much as it spent on HCV drugs for the entirety of 2014, according to a report co-published by ProPublica and The Washington Post.

The latest hep C price points, which journalists requested from the federal government through a freedom of information request, have raised huge concerns among federal health officials about how the taxpayer-funded program will be able to keep up with the growing demand for liver disease treatment.

According to the report, between January and June 2015, U.S. pharmacies filed more than 183,000 prescriptions for HCV drugs. Medicare paid for an estimated 119,033 prescriptions for Gilead Sciences’ Harvoni (ledipasvir/sofosbuvir), 23,933 prescriptions for Sovaldi (sofosbuvir) and 3,352 prescriptions for AbbVie’s Viekira Pak (ombitasvir/paritaprevir/ritonavir, dasabuvir) in that six-month period.

These preliminary numbers put the Part D program on track to outpace the nearly 288,000 HCV prescriptions filed in 2014. An average 12-week course of treatment with the most popular hep C drug, Harvoni, costs nearly $95,000 per patient, while the cheapest treatment, Viekira Pak, costs up to $83,320 for a comparable duration.

Fortunately, rebates from pharmaceutical companies are eventually expected to reduce the federal program’s multibillion-dollar bill by up to 50 percent by the end of 2015. However, even with the rebates, this year’s hep C costs are still expected to be far higher than in 2014. Experts believe 2016 is probably going to be even more expensive.

Some studies show that even with their high price tags, the long-term preventive costs of hep C treatment justify the short-term uptick in health expenses used to pay for new drugs. However, several states have already started restricting HCV treatment to only their sickest patients to help mitigate their impending health care bills.