Correlates of Susceptibility to Hepatitis B among People Who Inject Drugs in Sydney, Australia

Abstract

Despite a safe, effective vaccine, hepatitis B virus (HBV) vaccination coverage remains low among people who inject drugs (PWID). Characteristics of participants screened for a trial investigating the efficacy of financial incentives in increasing vaccination completion among PWID were examined to inform targeting of vaccination programs. Recruitment occurred at two health services in inner-city Sydney that target PWID. HBV status was confirmed via serological testing, and questionnaires elicited demographic, drug use, and HBV risk data. Multinomial logistic regression was utilized to determine variables independently associated with HBV status. Of 172 participants, 64% were susceptible, 17% exposed (HBV core antibody-positive), and 19% demonstrated evidence of prior vaccination (HBV surface antibody ≥ 10 mIU/ml). Compared with exposed participants, susceptible participants were significantly more likely to be aged less than 35 years and significantly less likely to be receiving current opioid substitution therapy (OST) and to test hepatitis C antibody-positive. In comparison to vaccinated participants, susceptible participants were significantly more likely to be male and significantly less likely to report daily or more frequent injecting, current OST, and prior awareness of HBV vaccine. HBV vaccination uptake could potentially be increased by targeting younger, less frequent injectors, particularly young men. In addition to expanding vaccination through OST, targeting "at risk" youth who are likely to have missed adolescent catch-up programs may be an important strategy to increase coverage. The lack of an association between incarceration and vaccination also suggests increasing vaccination uptake and completion in adult and juvenile correctional facilities may also be important.

Addressing viral hepatitis in the opiate substitution setting: An integrated nursing model of care

“…Given the serious sequelae of chronic HBV, prevention is a priority. Overall, studies indicate that 14% to 46% of PWID in Australia are susceptible to HBV, yet many in this cohort believe that they are immune to infection . The uptake of the HBV vaccine is low in PWID.…”

“…In Australia, an estimated 41% to 68% of people who inject drugs (PWID) are HCV positive, and between 28% and 59% of users are estimated to have been exposed to HBV (HBV core antibody [HBcAb‐positive]) while 26% to 33% have evidence of vaccine‐induced immunity (HBV surface antibody [HBsAb] ≥ 10 IU/mL and HBcAb negative) . Around 5% are HBsAg positive .…”

“…In a recent Australian study of 172 PWID, only 19% had evidence of prior vaccination. When compared with vaccinated participants, unvaccinated susceptible PWID were significantly more likely to be male and significantly less likely to report daily or more frequent injecting, current opioid substitution treatment (OST), and awareness of the HBV vaccine …”

“…2 In Australia, an estimated 41% to 68% of people who inject drugs (PWID) are HCV positive, 2 and between 28% and 59% of users are estimated to have been exposed to HBV (HBV core antibody [HBcAb-positive]) while 26% to 33% have evidence of vaccineinduced immunity (HBV surface antibody [HBsAb] ≥ 10 IU/mL and HBcAb negative). 4 Around 5% are HBsAg positive. 5 The prevalence of the latter is substantially lower than that of HBcAb positivity because, among adolescents and young adults, the rates of spontaneous HBsAg clearance are high, explaining the considerably lower proportion of PWID among the population with chronic HBV compared with newly acquired infection.…”

Hepatitis B vaccination in clients attending for opiate replacement therapy: Opportunism is key

“…A safe and effective vaccine against hepatitis B is available and, when administered to IDUs in Western Australia, the cost is met by the Department of Health [1]. Despite this, hepatitis B vaccination rates in IDUs are lower than in the general population, with studies suggesting that only between 19% and 37% of IDUs have evidence of vaccine-induced immunity [2][3][4].…”