Online interventions to reduce stigma towards population groups affected by blood borne viruses in Australia

•Short online videos demonstrate short term effectiveness in reducing stigmatising attitudes among the general public in Australia•Some positive changes in attitudes towards population groups affected by blood borne viruses were maintained by three-month follow-up•Political conservatism was the strongest predictor of holding negative attitudes towards people affected by blood borne viruses Stigmatising attitudes and behaviours by others can have a range of negative effects for population groups and individual people affected by blood borne viruses. The reduction of stigma is a major goal within current Australian national health strategies, however, there is a lack of evidence regarding effective interventions to achieve this goal. Drawing on Allport's (1954) intergroup contact theory, this study aimed to evaluate the effectiveness of an online stigma reduction intervention implemented with the Australian public. The study was conducted between February and May 2020. Australian adults recruited via Facebook advertising were randomly allocated to a control group (n=316) or one of five intervention groups: people living with HIV (n=320), people living with hepatitis C (n=347), people living with hepatitis B (n=333), people who inject drugs (n=316), or sex workers (n=296). Participants viewed a short video depicting lived experiences of their assigned group. Participants completed attitudinal measures about the group before and immediately after the video, and then at three-month follow-up. These measures related to overall attitudes towards the group, controllability of the stigmatised condition/behaviour, desire to maintain personal distance from the group, and opinions regarding treatment of the group in health care and public policy. Longitudinal changes in attitudes were analysed using a mixed effects regression model with maximum likelihood estimation. Across each of the intervention groups, reductions in negative attitudes were found immediately after watching the videos on almost all outcome measures. By three-month follow-up, the HIV intervention group demonstrated long-term improvements in relation to personal distance compared to the control group, and the hepatitis B intervention group demonstrated long-term improvements in relation to attitudes and personal distance compared to the control group. Across intervention and control groups, long-term reductions in negative attitudes were found in relation to HIV controllability, hepatitis B controllab