A randomised controlled trial of financial incentives to increase hepatitis B vaccination completion among people who inject drugs in Australia

• Hepatitis B vaccination completion rates are low among people who inject drugs.
• First head-to-head randomised trial of financial incentives for vaccination completion
• Those who received financial incentives were more likely to complete.
• The strategy may also be useful for other vaccine preventable infections.

ObjectiveThis study aimed to investigate the efficacy of modest financial incentives in increasing completion of an accelerated 3-dose hepatitis B virus (HBV) vaccination schedule (0, 7, 21 days) among people who inject drugs (PWID).MethodsRandomised controlled trial. Participants were randomly allocated to receive $30 Australian Dollars cash following receipt of vaccine doses two and three (‘incentive condition’), or standard care (‘control condition’). Serologically confirmed HBV-susceptible PWID. Two inner-city health services and a field study site in Sydney, Australia. The primary outcome was completion of the vaccination series. Additional assessments included self-reported demographic, drug use and treatment, and risk-taking histories.ResultsCompared to the control condition, significantly more participants in the incentive condition received all three vaccine doses, under intention-to-treat analyses (n = 139; 87% versus 66%; p = .004); and within the specified window periods under per protocol analyses (n = 107 received three vaccine doses; 92% versus 67%; p = .001). Multivariate analysis indicated that the incentive condition and longer injecting histories significantly increased the likelihood of series completion. Aboriginal/Torres Strait Islanders were significantly less likely to complete the series.ConclusionsModest financial incentives, per-dose, increased adherence to the accelerated HBV vaccination schedule among PWID. Results have implications for increasing HBV and, potentially, other vaccine-preventable infections, among PWID.