Novel treatments for hepatitis Delta virus (HDV) infection provide promising opportunities to treat patients with hepatitis B virus (HBV) and HDV co-infection. However, current clinical trials on HDV treatment rarely explore patients' barriers to treatments. In Europe, HDV infection mostly affects young migrants from HDV-endemic areas who experience early liver-related mortality. Migrants are more likely to face multiple situations of statutory and socioeconomic insecurity and structural barriers than non-migrants. These obstacles may impact their quality of life and can (i) lead them to give secondary importance to certain HDV care options, (ii) delay treatment initiation and (iii) affect their adherence and commitment to care.Preliminary results from the ANRS CO22 HEPATHER cohort show that the majority (61.6%) of HBV-HDV coinfected migrants live in poverty. Moreover, half were diagnosed and a quarter of those who initiated HBV treatment had been in France for no more than two years, a period when language skills are often still poor and when knowledge of the health and administrative system may be lacking. We advocate for increased social science research, in particular qualitative studies, to investigate the effects that multiple forms of precarity (weak access to social rights, language barriers, housing insecurity, unexpected expenditures and other difficulties) may have on HDV screening opportunities, follow-up, and treatment pathways in migrants. This will help adapt communication and care around viral hepatitis, as well as inform and orient medical services and public health actors about the difficulties that migrants encounter. co-infected; n = 3375 HBV mono-infected.

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