New research from the Centers for Disease Control and Prevention (CDC) suggests that the recent steep increase in cases of acute hepatitis C virus infection is associated with increases in opioid injection. The study examines data from CDC’s hepatitis surveillance system and from the Substance Abuse and Mental Health Services Administration’s national database that tracks admissions to substance use disorder treatment facilities in all 50 states. Across the nation, researchers found substantial, simultaneous increases in acute hepatitis C (133 percent) and admissions for opioid injection (93 percent) from 2004 to 2014. These increases were seen at not only the national level, but also when data were analyzed by state, by age, and by race and ethnicity. Taken together, the findings point to a close relationship between the two troubling trends.