Homeless participants in each group were offered the three-series Twinrix HAV (inactivated) and HBV (recombinant) vaccine by a study nurse blinded to the group assignment. The Twinrix was used because it would vaccinate homeless persons for HAV while vaccinating against HBV and still maintain the same 6-month timeframe as for the HBV vaccination series (0, 1, and 6 months). As homeless persons are generally also at risk of HCV and HIV, for which no vaccinations yet exist, in addition to education and counseling for HBV and HAV, education and counseling for HCV and HIV were also provided to all participants. Subsequently, participants had a 10-minute period to discuss questions with the nurse before they presented for each dose of the Twinrix vaccine series. Two nurse and outreach teams worked exclusively with participants in either the intervention or control programs. A team of outreach workers not involved in the programs provided tracking and follow-up on all participants for their 6-month questionnaire.