Pan-Viral Screening and Linkage to Care Among GBMSM and Trans Women in Spain

The World Health Organization (WHO) aims to eliminate viral hepatitis as a public health threat by 2030, with major reductions in hepatitis B and C incidence and mortality. However, hepatitis C virus (HCV) transmission has increased among gay, bisexual, and other men who have sex with men (GBMSM), especially those living with HIV. Practices such as chemsex, particularly involving injection drug use, have contributed to this rise. Hepatitis B virus (HBV) also remains a public health challenge due to the potential for chronic infection and severe liver damage. Hepatitis D virus (HDV), which requires HBV co-infection, further complicates clinical management. This study aims to design, implement, and evaluate an online self-sampling testing strategy to enhance pan-viral testing (HBV, HCV, HDV, HIV) and improve linkage to care among GBMSM and transgender women (TW) in Spain. The intervention will involve self-collected dried blood spot (DBS) samples for testing HBV surface antigen (HBsAg), HIV antibodies, and HCV RNA. Individuals testing positive for HBsAg will undergo further testing for HBV DNA and HDV infection. Those lacking protective levels of HBV antibodies will be referred for vaccination or revaccination. The study will also assess the number of HIV-positive individuals who acquired the infection while waiting for access to PrEP, identifying missed prevention opportunities. This non-randomized, single-arm, prospective national study will recruit adult GBMSM and TW through PrEP services, dating apps, NGOs, social media, and community outreach. Participants will complete an online risk assessment (using the HCV-MOSAIC algorithm) and receive self-sampling kits with instructions, lancets, Whatman cards, and prepaid envelopes. Results will be provided online, and those testing positive will be linked to confirmatory diagnosis and care. Outcomes include estimates of HIV, HBV, HCV, and HDV prevalence; effectiveness of linkage to care; acceptability and usability o