More than 2 million people in the United States have hepatitis C virus (HCV), according to new statistics from the Centers for Disease Control and Prevention (CDC), and the opioid crisis is a major driver of the crisis, WebMD reports

The CDC’s latest statistics on hepatitis C highlight both the progress and the hard work that still must be done to combat the potentially deadly liver virus. According to the study, nearly 2.4 million Americans were living with hepatitis C between 2013 and 2016—a small decline from previous years. 

Officials say the positive effects of new treatments are helping to combat hepatitis C across the country. However, they say deaths among older HCV-positive Americans may also account for part of the decline. What’s more, new figures show the majority of people in the United States who need treatment have not yet accessed it. 

Meanwhile, new hepatitis C infections have tripled between 2010 and 2016, and most have been traced back to injection drug use among adults under 40. 

“The opioid crisis is sabotaging our progress against hepatitis C,” said Jonathan Mermin, MD, who worked on the CDC study. 

In addition to expanding access to hepatitis C treatment, CDC officials recommend opening up more syringe exchange programs and other harm reduction services that help prevent infections.