The 'Viennese epidemic' of acute HCV in the era of direct-acting antivirals

The recently reported epidemic of acute hepatitis C virus (HCV) infections -observed predominantly among men who have sex with men (MSM)-may now decline due to wide availability of direct-acting antivirals (DAAs). This study aimed to investigate the current trends of acute hepatitis C in Vienna. Patients presenting with acute hepatitis C between 01/2007 and12/2020 at the Vienna General Hospital were retrospectively enrolled and followed after virologic clearance/eradication. The introduction of unrestricted DAA access after 09/17 defined the 'DAA era', as compared to the 'pre-DAA era' prior to 09/17. We identified 134 acute hepatitis C cases in 119 patients with a mean age of 39 +/- 9 years at inclusion. The majority of patients were male (92%), HIV-positive (88%) and MSM (85%). In the DAA era, a history of prior chronic HCV infection at inclusion was found in 24% (11/46) compared to 7% (5/73) in the pre-DAA era (p = .012). The annual rate of acute hepatitis C cases increased in the DAA era (17.11 per year) compared to the pre-DAA era (7.76 per year). The DAA era included an AHC-genotype-2 cluster and more HIV-negative acute hepatitis C cases (0% (0/73) vs. 30% (14/46), p < .001). Patients were followed after spontaneous clearance or sustained virologic treatment response (SVR) for a total of 251.88 patient-years (median 1.39 years per patient). In the DAA era, we recorded 15 acute hepatitis C-reinfections - corresponding to an incidence rate of 5.96 (95% CI: 3.57-9.66) reinfections per 100-patient-years. We continue to observe a high incidence of acute hepatitis C in Vienna in the DAA era-primarily among HIV-positive MSM, but increasingly also in HIV-negative MSM.