Theme: Epidemiology & Public Health Research Year: 2015
Background: People who inject drugs (PWID) are at risk of hepatitis B virus (HBV) infection through unsafe injecting practices and unprotected sexual activity. Despite availability of an effective vaccine, in a Melbourne-based cohort of PWID, about 20% were identified as susceptible to HBV. We aimed to improve HBV vaccination uptake and immunity by offering opportunistic vaccination to this cohort.
Methods: HBV serologically naïve PWID in the Melbourne-based SuperMIX cohort were eligible for HBV vaccination. Participants were randomised to receive either a standard vaccination course (three doses at 0, 1 and 6 months) or an opportunistically-delivered course (three doses at least 7 days apart with one dose 12-months later. A nurse immuniser delivered vaccination in the field using assertive outreach to maximise completion. Vaccine completion and immunity (measured by HBV surface antibody titre >10 U/l) after vaccination were the primary outcomes.
Results: Fifty PWID were recruited and thirty-eight participants (76%) completed three vaccination doses: two participants withdrew from the standard arm and ten were lost to follow up (four, standard arm; six, opportunistic arm). Three-dose vaccination completion was the same using the standard versus opportunistic schedule: 19/25 (76%) versus 19/25 (76%). However, in the opportunistic arm vaccination uptake at 12-months was lower (12/25, 48%; p=0.041). In intention-to-treat-analysis, protective immunity was detected among 9/25 (36%) of those who received the standard schedule compared with 13/25 (52%) who received opportunistic vaccination (p=0.254). In per-protocol analysis, after three vaccine doses protective immunity was lower among those who received the standard schedule (9/19, 47%) compared with those who received opportunistic vaccination (13/16, 82%) (p=0.039).
Conclusion: We found moderately-high uptake of HBV vaccination among our cohort of PWID using assertive field-based outreach. Findings suggest opportunistic three-dose vaccination is feasible and an effective alternative to standard vaccination schedules in hard to reach populations.Download abstract