After Zepatier (grazoprevir/elbasvir) cured a high rate of individuals addicted to opioids of hepatitis C virus (HCV), few became reinfected during a large study’s long-term follow-up period, aidsmap reports.

Researchers from the multinational Zepatier Phase III C-EDGE CO-STAR study presented long-term follow-up data at the 25th International Harm Reduction Conference (HR17) in Montreal. The initial phase of the study included 301 first-timers to hep C treatment with genotypes 1, 4 or 6 of the virus. All had been taking opioid substitution therapy, including methadone or buprenorphine, for at least three months prior to entering the study. All were given 12 weeks of Zepatier.

As reported in 2015, in Part A of the study, 91 percent of the participants achieved a sustained virologic response 12 weeks after completing therapy (SVR12, considered a cure). When calculating this cure rate, the investigators considered those reinfected during a 12-month follow-up period as not having been cured. If the reinfected individuals had been categorized as cured, the cure rate would have been 96 percent.

During Part B of the study, 199 members of Part A were followed for up to three years post-treatment. The participants made twice-yearly visits to this phase of the study. A total of 192 people completed an additional six months of follow-up; 161 people completed an additional 12 months of follow-up; and 17 people completed an additional 18 months of follow-up.

Through 12 weeks post-Zepatier treatment, five participants were reinfected with hep C. Another one was reinfected at week 24. Two more were reinfected by their first visit for Part B of the study. A total of eight reinfections translated to a reinfection rate of 4 percent per year. Considering that three of these individuals spontaneously cleared the reinfection without any medical intervention, the reinfection rate was in fact only 2.5 percent.

To read the aidsmap article, click here.

To read the conference abstract, click here.