Although rates of acute hepatitis C virus (HCV) infections have declined over the past decade across Europe, a small increase in reinfections was seen among men who have sex with men (MSM), according to a German prospective observational study.

Among 161 patients with acute HCV infection, 87% of whom were HIV-positive and 90% of whom identified as MSM, 14% experienced a reinfection, with reinfection rates increasing from 1.9 to 2.7 per 100 person-years, with low spontaneous clearance rates, over the period of 2009 to 2019, reported Christiana Graf, MD, of Goethe University Hospital Frankfurt in Germany.

“We identified an ongoing risk of repeated HCV transmission among MSM,” Graf noted during the European Association for the Study of the Liver (EASL) annual meeting. “Thus, for treatment surveillance, rapid diagnosis and prioritizing those with recently acquired HCV infection is crucial to achieving HCV elimination.”

Among MSM, the cumulative incidence of a first HCV infection decreased over the study period:

• Pre-direct-acting antiviral (DAA) era from 2009 to 2013: 8.3 per 1,000 person-years
• First-generation DAA era from 2013 to 2017: 5.9 per 1,000 person-years
• Second-generation DAA era from 2017 to 2019: 3.3 per 1,000 person-years

“The decline in the HCV incidence rate among MSM overall in the DAA era is reassuring,” Anthony Martinez, MD, of the University at Buffalo in New York, who was not involved in this study, told MedPage Today. “But the study also speaks to the need for continued screening among this high-risk cohort based on the reinfection rate.”

Of note, the incidence of acute HCV has increased among younger people in the U.S. Prior studies have found that MSM and injection drug users who are co-infected with HCV and HIV have different phylogenetic clustering of HCV strains.

For this study, Graf and colleagues examined data on 161 patients (mean age 42) with acute HCV infection from 2009 to 2019 across three centers in Frankfurt. Nearly all were MSM (n=145), and 140 patients were HIV positive.

In order to identify phylogenetic clusters, the researchers conducted nonstructural protein 5B (NS5B) population-based sequencing on 213 patients with acute and chronic HCV (the 161 included in the study plus 52 from the European Resistance Database), which showed a variable distribution of HCV genotypes over time.

All clusters were MSM-specific and were distinct for MSM and injection drug users, with considerable overlap of European, Canadian, and Australian transmission networks.

During the first 8 years of the study, the GT1a HCV genotype was the most common, which decreased in incidence by 2018, along with the GT1b and GT2 genotypes. Despite no cases of GT4d being diagnosed in 2013, the proportion of cases increased to 40% by 2019. From 2018 to 2019, there was a slight trend that suggested a rise in GT3a cases.

Among the MSM included in this study, most were infected with GT1a (80%), followed by GT4d (17%). The HCV strains among MSM with GT1a and GT4d were found to be more closely related. An almost equal distribution of genotypes were detected among non-MSM patients.

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