Immunity to hepatitis A when outbreaks of infection in men who have sex with men (MSM) are rare

► Hepatitis A is rare in MSM in Victoria but immunity levels are unknown. ► This study was a retrospective analysis of MSM 12,064 attending a clinic. ► About 40% of MSM had antibodies to hepatitis A. ► About 50% of MSM had a record of past hepatitis A vaccine. ► To prevent further outbreaks, levels of immunity should be maintained above 40-50%.