Incidence of hepatitis C virus antibody seroconversion among people who inject drugs in Tbilisi, Georgia, 2017-2019.

BACKGROUND: Georgia launched a hepatitis C elimination program in 2015, and prioritized reducing hepatitis C virus (HCV) infections among people who inject drugs (PWID). METHODS: To assess the effectiveness of the program, we established a prospective observational cohort study to estimate incidence of HCV antibody (anti-HCV) seroconversion among PWID in Tbilisi during 2017-2019. Participants were recruited using incentivized chain-referral sampling. Incidence of anti-HCV seroconversion was calculated as the number of seroconversions divided by total person-years of follow-up (PYFU). Crude estimates were adjusted using post-stratification weights. Factors associated with seroconversion were evaluated in a Cox proportional hazards regression model. RESULTS: Among 1,744 PWID enrolled, 563 (32.3%) were anti-HCV reactive at baseline and were excluded from follow-up. Among the remaining 1,181 anti-HCV nonreactive PWID, 929 (78.7%) returned for at least one visit and were followed-up for a mean of 11.7 months, contributing a total 906 PYFU. During follow-up, 7 (0.8%) persons seroconverted. After adjusting for age, sex, and sharing injection equipment, the incidence rate of new infections was 0.9 (95% confidence interval [CI]: 0.4-1.7) per 100 PYFU. In regression analysis, only history of sharing injection equipment was associated with seroconversion (hazard ratio: 50.5, 95% CI: 2.5-611.6). CONCLUSION: Our findings suggest that the HCV elimination program in Georgia has been successful in limiting transmission among PWID, however this population remains at risk of contracting HCV. Expansion of harm reduction services and integration of HCV diagnostics and treatment may help prevent new HCV infections to promote hepatitis C elimination among PWID.