SHM contributes to the MSM Observational Study of Acute Infection with Hepatitis C (MOSAIC) study coordinated by the GGD Amsterdam. The MOSAIC study involves a cohort of men who have sex with men (MSM) with chronic HIV infection who have contracted an acute hepatitis C (HCV) infection. The aims of the study are to look at how this group contributes to the transmission of HIV; to explore the driving factors of the HCV epidemic and HIV’s role in it; and to examine the impact of acute HCV infection, reinfection and treatment on disease progression. SHM and GGD Amsterdam also work together on the Amsterdam Cohort Studies (ACS, reviewed earlier in this report), in collaboration with the AMC-UvA. The ACS is primarily funded through the CIb-RIVM and, as of 1 January 2015, the funding is included in the structural institute grant awarded to SHM by the CIb-RIVM.