Long-term effectiveness of accelerated hepatitis B vaccination schedule in drug users

Hepatitis B Vaccine: Four Decades on

Hepatitis B virus is a substantial contributor to cirrhosis and hepatocellular carcinoma (HCC) globally. Vaccination is the most effective method for prevention of hepatitis B and its associated morbidity and mortality, and the only method to prevent infection with hepatitis D virus. The hepatitis B vaccine has been used worldwide for more than four decades; it is available in a single- or triple-antigen form and in combination with vaccines against other infections. Introduction of the vaccine and administration at birth led to sustained decline in mother-to-child transmission, chronic hepatitis B, and HCC, however, global birth dose coverage remains suboptimal. In this review we will discuss different hepatitis B vaccine formulations and schedules, vaccination guidelines, durability of the response, and vaccine escape mutants, as well as the clinical and economic benefits of vaccination.

Predictors of Hepatitis B screening and vaccination status of young psychoactive substance users in informal settlements in Kampala, Uganda

BACKGROUND

Young psychoactive substance users exhibit high-risk behaviours such as unprotected sexual intercourse, and sharing needles and syringes, which increases their risk of Hepatitis B infection. However, there is limited evidence of screening, and vaccination status of this subgroup. The aim of this study was to establish the predictors of screening and completion of the hepatitis B vaccination schedule.

METHODS

A cross-sectional study using respondent driven sampling was used to enrol respondents from twelve out of fifty-seven informal settlements in Kampala city. Data were collected using an electronic structured questionnaire uploaded on the KoboCollect mobile application, and analysed using Stata version 14. A "modified" Poisson regression analysis was done to determine the predictors of screening while logistic regression was used to determine the predictors of completion of the Hepatitis B vaccination schedule.

RESULTS

About 13.3% (102/768) and 2.7% (21/768) of the respondents had ever screened for Hepatitis B, and completed the Hepatitis B vaccination schedule respectively. Being female (aPR 1.61, 95% CI: 1.11-2.33), earning a monthly income >USD 136 (aPR 1.78, 95% CI: 1.11-2.86); completion of the Hepatitis B vaccination schedule (aPR 1.85, 95% CI: 1.26-2.70); lack of awareness about the recommended Hepatitis B vaccine dose (aPR 0.43, 95% CI: 0.27-0.68); and the belief that the Hepatitis B vaccine is effective in preventing Hepatitis B infection (aPRR 3.67, 95% CI: 2.34-5.73) were associated with "ever screening" for Hepatitis B. Knowledge of the recommended Hepatitis B vaccine dose (aOR 0.06, 95% CI: 0.01-0.35); "ever screening" for hepatitis B (aOR 9.68, 95% CI: 2.17-43.16) and the belief that the hepatitis B vaccine is effective in preventing Hepatitis B infection (aOR 11.8, 95% CI: 1.13-110.14) were associated with completion of the hepatitis B vaccination schedule.

CONCLUSIONS

Our findings indicate a low prevalence of Hepatitis B screening and completion of the Hepatitis B vaccination schedule among young psychoactive substance users in informal settings. It is evident that lack of awareness about Hepatitis B is associated with the low screening and vaccination rates. We recommend creation of awareness of Hepatitis B among young people in urban informal settlements.

Two-year immune effect differences between the 0-1-2-month and 0-1-6-month HBV vaccination schedule in adults

Background

The short-term 0–1–2-month hepatitis B virus (HBV) vaccination schedule was previously implemented in the adult population; however, its long-term immune effect remains unclear. The present study aimed to investigate (1) the 2-month and 2-year immune effects of HBV vaccination and (2) the compliance rate between the 0–1–2-month and 0–1–6-month vaccination schedules in adults.

Method

A total of 1281 subjects tested for hepatitis B surface antigen HBsAg(−) and hepatitis B surface antibody (anti-HBs)(−) were recruited. Participants from two distant counties were inoculated with the hepatitis B yeast vaccine at 10 µg per dose, with vaccination schedules of 0, 1, and 2 months (n = 606) and 0, 1, and 6 months (n = 675); sequential follow-up was performed at 2 months and 2 years after the 3rd injection.

Results

There were no significant differences in the anti-HBs seroconversion rates between the those in the 0–1–2-month and 0–1–6-month vaccination schedule groups at 2 months (91.96% vs. 89.42%, p = 0.229) and 2 years (81.06% vs. 77.14%, p = 0.217). The quantitative anti-HBs level in those in the 0–1–2-month vaccination schedule group was not different from that in those in the 0–1–6-month vaccination schedule group at 2 months (anti-HBs₁) (342.12 ± 378.42 mIU/ml vs. 392.38 ± 391.96 mIU/ml, p = 0.062), but it was higher at 2 years (anti-HBs₂) (198.37 ± 286.44 mIU/ml vs. 155.65 ± 271.73 mIU/ml, p = 0.048). According to the subgroup analysis, the 0–1–2-month vaccination schedule induced better maintenance (p = 0.041) and longer reinforcement (p = 0.019) than the 0–1–6 vaccination schedule. The 0–1–2-month vaccination schedule group also had a higher 3rd injection completion rate (89.49% vs. 84.49%, p = 0.010).

Conclusion

The 0–1–2-month vaccination schedule was associated with a similar short-term immune effect and might induce better long-term immune memory and a higher completion rate in the adult population.

Trial registration None

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07151-6.

Immunogenicity, safety, and compliance of high- and standard-strength four-dose hepatitis B vaccination regimens in patients receiving methadone maintenance therapy in China: a randomized, parallel-arm controlled trial

BACKGROUND

We evaluated the safety and immunogenicity of four doses of 20 or 60 µg, and the immunogenicity and compliance of the short-term vaccination regimen (0, 1, and 2 months) among patients receiving MMT.

RESEARCH DESIGN AND METHODS

We conducted a randomized controlled trial among 303 patients receiving MMT who were randomized to receive 3 or 4 doses of 20 or 60 µg of recombinant hepatitis B vaccine.

RESULTS

At month 7, the seroconversion rates in both IM20 × 4 and IM60 × 4 groups were numerically higher than the IM20 × 3 group (P > 0.05). The high-level responses and geometric mean concentration (GMC) of anti-HBs in both IM20 × 4 and IM60 × 4 groups were significantly higher than the IM20 × 3 group (P < 0.05). The completion rate of the short-term high-strength vaccination group was significantly higher than the standard vaccination group (P < 0.05), with similar immunogenicity (P > 0.05).

CONCLUSIONS

Both the high-strength and standard-strength four-dose hepatitis B vaccine regimens could improve the immune response for patients receiving MMT. The high-strength short-term vaccination regimen could improve compliance and attain comparable immunogenicity with the standard vaccination regimen. The high-strength short-term vaccination regimen is recommended and the fourth dose is encouraged for this population considering the compliance and immunogenicity.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT03962816).

Unequal impact of the COVID-19 crisis on minority ethnic groups: a framework for understanding and addressing inequalities

Minority ethnic groups have been disproportionately affected by the COVID-19 pandemic. While the exact reasons for this remain unclear, they are likely due to a complex interplay of factors rather than a single cause. Reducing these inequalities requires a greater understanding of the causes. Research to date, however, has been hampered by a lack of theoretical understanding of the meaning of ‘ethnicity’ (or race) and the potential pathways leading to inequalities. In particular, quantitative analyses have often adjusted away the pathways through which inequalities actually arise (ie, mediators for the effect of interest), leading to the effects of social processes, and particularly structural racism, becoming hidden. In this paper, we describe a framework for understanding the pathways that have generated ethnic (and racial) inequalities in COVID-19. We suggest that differences in health outcomes due to the pandemic could arise through six pathways: (1) differential exposure to the virus; (2) differential vulnerability to infection/disease; (3) differential health consequences of the disease; (4) differential social consequences of the disease; (5) differential effectiveness of pandemic control measures and (6) differential adverse consequences of control measures. Current research provides only a partial understanding of some of these pathways. Future research and action will require a clearer understanding of the multiple dimensions of ethnicity and an appreciation of the complex interplay of social and biological pathways through which ethnic inequalities arise. Our framework highlights the gaps in the current evidence and pathways that need further investigation in research that aims to address these inequalities.

Acceptability of on-site rapid HIV/HBV/HCV testing and HBV vaccination among three at-risk populations in distinct community-healthcare outreach centres: the ANRS-SHS 154 CUBE study

BACKGROUND

HIV, HBV and HCV infections continue to represent major health concerns, especially among key at-risk populations such as men who have sex with men (MSM), people who inject drugs (PWIDs), transgender women (TGW) and sex workers (SW). The objective of the ANRS-CUBE study was to evaluate the acceptability of a healthcare, community-based strategy offering a triple rapid HIV-HBV-HCV testing, and HBV vaccination, targeted at three priority groups (MSM, PWIDs and TGW/SWs), in three community centers, in the Paris area.

METHODS

This longitudinal multicentric non-randomized study included all adult volunteers attending one of the three specialized community centers in Paris, between July 2014 and December 2015. HIV, HBV and HCV status and acceptability of HBV vaccination were evaluated.

RESULTS

A total of 3662, MSM, 80 PWIDs and 72 TGW/SW were recruited in the three centers respectively. Acceptability of rapid tests was 98.5% in MSM and 14.9% in TGW/SWs, but could not be estimated in PWIDs since the number of users attending and the number of proposals were not recorded. User acceptability of HBV vaccination was weak, only 17.9% of the eligible MSM (neither vaccinated, nor infected) agreed to receive the first dose, 12.2% two doses, 5.9% had a complete vaccination. User acceptability of HBV vaccination was greater in PWIDs and TGW/SWs, but decreased for the last doses (66.7 and 53.3% respectively received a first dose, 24.4 and 26.7% a second dose and 6.7 and 0% a third dose). Fifty-three participants (49 MSM and 4 PWIDs) were discovered HIV positive, more than half with a recent infection. All but two HIV positive participants were linked to appropriate care in less than one month.

CONCLUSIONS

Rapid HIV-HCV-HBV screening showed a very high level of acceptability among MSM. Efforts need to be made to improve immediate acceptability for HBV vaccination, especially among MSM, and follow-up doses compliance. Our results show the important role of community centers in reaching targets, often fragile, populations, while also suggesting the need to reinforce on-site human support in terms of testing and vaccination, especially when addressing PWIDs.

Long-term durability of immunogenicity induced by standard and triple-dose hepatitis B vaccine in patients receiving methadone maintenance treatment

OBJECTIVES

We explored the long-term immunogenicity induced by 60 μg and 20 μg hepatitis B vaccines among patients receiving methadone maintenance treatment (MMT).

METHODS

In initial study, a randomized controlled trial was conducted, in which patients receiving MMT were administered 20 µg (IM20 group) or 60 µg (IM60 group) hepatitis B vaccines at months 0, 1, and 6. In this study, the responders at month 7 were followed-up at months 18, 30, and 42 to estimate long-term immunogenicity.

RESULTS

The response rate decreased from 78.0% (39/50) to 31.1% (14/45) in the IM20 group, and from 86.0% (43/50) to 50.0% (20/40) in the IM60 group from month 7 to 42. Vaccine-induced responses in 75% of patients were observed for 14.2 months in the IM20 group and for 20.0 months in the IM60 group, and differences between these two groups were non-significant (P > 0.05).

CONCLUSION

The three-dose 20 µg and 60 µg hepatitis B vaccines showed similar rapid hepatitis B surface antibody decreases. Abbreviations: HBV, hepatitis B virus; MMT, methadone maintenance treatment; HCC, hepatocellular carcinoma; HBsAg, hepatitis B surface antigen; anti-HBs, hepatitis B surface antibody; HR, hazard ratio; CI, confidence interval; IQR, interquartile range; GEE, generalized estimated equation.

Effectiveness Analysis of the Immunization Against Hepatitis B in Liver Transplantation Patients

OBJECTIVE

This article analyzes the effectiveness of a super-accelerated immunization schedule against hepatitis B in patients who have received a liver transplantation.

METHODS

This is a quantitative and retrospective study based on secondary data of medical records from 177 patients who have received a liver transplantation at the Hospital de Base in São José do Rio Preto, São Paulo State, Brazil, between 1998 and 2016.

RESULTS

From the total number of participants, 72.89% were male, 39.55% had a cirrhosis diagnosis with associated causes, 23.16% had hepatocellular carcinoma, 53.11% were classified according to Child-Turcotte-Pugh C score, 58.76% had the hepatitis C virus, 97.18% had received an unconventional immunization schedule, and seroconversion was 36.63% among those with an unconventional schedule. The fact that the patient had the hepatitis C virus was statistically significant considering the lack of protection of the vaccine against the hepatitis B virus; their chances were 5 times higher of not seroconverting at the end of the immunization schedule.

CONCLUSION

The need for high immediate protection in a short term may justify using unconventional immunization schedules in patients who make it to the transplantation waiting list without any previous immunization.

Incident hepatitis B virus infection and immunisation uptake in Australian prison inmates

INTRODUCTION

Despite an effective vaccine, hepatitis B virus (HBV) infection continues to impose a large burden of disease globally. Until childhood immunisation achieves high adult population coverage, people who inject drugs (PWID), including prison inmates remain at risk. PWID have a higher prevalence of HBV than the wider population, and lower rates of vaccine-conferred immunity. This study sought to identify the incidence and predictors of HBV transmission and uptake of immunisation in PWID prisoners in Australia.

METHODS

Longitudinally collected, stored sera from subjects previously enrolled in a prospective study of hepatitis C in recently incarcerated PWID prisoners (n = 590) were serologically tested for HBV. Interviews recording demographic and behavioural risks were analysed. Multivariate statistical analyses were applied to identify associations of incident infection or immunisation.

RESULTS

Upon imprisonment there were n = 373 (63%) individuals who were HBV susceptible, of whom 140 remained susceptible at the subsequent enrolment into the cohort, and had one or more follow-up visits (a total of 406.73 person years [p.y.]), and so were included in this analysis. There were 7 incident cases of HBV infection (1.7 per 100 p.y.) in this group, with transmission being associated with injecting drug use daily or more often. There were 48 individuals who were successfully immunised (11.8 per 100 p.y.) with younger age and continuous imprisonment predicting this outcome.

CONCLUSIONS

The Australian prison environment poses a high risk for HBV infection, and also provides an opportunity for immunisation for PWID. Further efforts are required to improve coverage and prevent ongoing transmissions.

Short-term immunogenicity of standard and accelerated hepatitis B virus vaccination schedules in healthy adults: a comparative field study in China

World Health Organization recommends hepatitis B virus (HBV) immunization at 0, 1, and 6 months. However, studies have suggested that shortening the interval between the first and last HBV immunization can improve completion rates. Less clear is whether accelerated immunization is as immunogenic as standard immunization. Thus, the present study aimed to compare the short-term immunogenicity of yeast-derived hepatitis B vaccine in healthy adults immunized on an accelerated or standard schedule. Between June 2013 and March 2014, individuals from Jinfeng and Longmen, China were randomly assigned to receive the vaccine on an accelerated schedule (at 0, 1, and 2 months; n=201) or a standard schedule (at 0, 1, and 6 months; n=206). Subjects filled out a questionnaire asking about demographic and other health data, and they underwent physical examination. Blood was assayed for HBV surface antigen and HBV surface antibody (HBsAb) at 1–2 months after the three-dose schedule. Multivariate binary logistic regression was used to determine whether the rate of anti-HBs seroconversion differed with immunization schedule. Covariance analysis was used to compare geometric mean HBsAb concentration between the two schedules. The anti-HBs seroconversion rate was 84.6% in the accelerated group and 90.3% in the standard group. After controlling for several potential confounders, the accelerated schedule was associated with significantly lower anti-HBs seroconversion rate (OR: 0.560, 95% CI: 0.318–0.988). Similarly, the accelerated schedule was associated with significantly lower geometric mean HBsAb concentration. These results suggest that the standard schedule is more likely to lead to anti-HBs seroconversion and higher HBsAb levels in adults.

Predictors of hepatitis B vaccination completion among people who use drugs participating in a national program of targeted vaccination

BACKGROUND

Targeted vaccination strategies are necessary to prevent people who use drugs (PWUD) becoming infected with hepatitis B virus (HBV). The aims of this study were to provide an overview of the activities for PWUD in a decentralised vaccination program in the Netherlands and to explore the determinants associated with completing a standard hepatitis B vaccination series.

METHODS

We used data for behavioural risk groups from the register of the national vaccination program. The data concerned PWUD who were immunised against hepatitis B in the Netherlands between 2002 and 2011. A standard series of three vaccinations (at 0, 1, and 6 months) was offered at inclusion and was continued if serological markers for past or chronic HBV infection were absent. Completion of a vaccination series (at least three vaccinations, irrespective of timing) was a dependent variable in our logistic regression analysis.

RESULTS

The program reached 18,054 PWUD. Of the 15,746 participants eligible for vaccination (i.e. they were neither carriers of hepatitis B nor immune to hepatitis B), 9089 (58%) completed a series of three hepatitis B vaccinations. Factors associated with a higher completion rate of a vaccination series (p < 0.01) were: starting vaccination in the earlier years of the program, older age of PWUD, intravenous drug use, vaccine administration by addiction care centres, and flexibility in location of vaccine delivery.

CONCLUSION

Despite using a standard HBV vaccination schedule and no financial incentives, vaccination completion among PWUD was relatively high. Our results suggest that flexibility of vaccination location and administration of vaccines by healthcare workers with sustainable contact with PWUD could improve vaccination programs for this risk group.

A large proportion of people who inject drugs are susceptible to hepatitis B: Results from a bio-behavioural study in eight German cities

BACKGROUND

People who inject drugs (PWID) are at high risk of hepatitis B virus (HBV) infection by sharing needles and drug use paraphernalia. In Germany, no routine surveillance of HBV prevalence and vaccination coverage among PWID exists.

METHODS

Socio-demographic and behavioural data were collected between 2011 and 2014 through face-to-face interviews, during a bio-behavioural survey of PWID recruited in eight German cities. Dried blood spots (DBS) prepared with capillary blood were tested for HBV markers. Factors associated with past/current HBV infection and vaccination status were analysed by univariable and multivariable analysis using logistic regression. The validity of self-reported HBV infection and vaccination status was analysed by comparison to the laboratory results.

RESULTS

Among 2077 participants, the prevalence of current HBV infection was 1.1%, of past HBV infection was 24%, and of vaccine-induced HBV antibodies was 32%. No detectable HBV antibodies were found in 43%. HBV infection status was significantly associated with study city, age, years of injecting, use of stimulants, migration status, and homelessness; HBV vaccination status was significantly associated with study city, age, and level of education. Correct infection status was reported by 71% and correct vaccination status by 45%.

CONCLUSIONS

HBV seroprevalence among PWID was about five times higher than in the general population in Germany, confirming PWID as an important risk group. Targeted information campaigns on HBV and HBV prevention for PWID and professionals in contact with PWID need to be intensified. Routinely offered HBV vaccination during imprisonment and opioid substitution therapy would likely improve vaccination rates among PWID.

T follicular helper cells and antibody response to Hepatitis B virus vaccine in HIV-1 infected children receiving ART

HBV vaccine has 95% efficacy in children to prevent HBV infection and related cancer. We conducted a prospective study in HIV-1 infected children receiving ART (n = 49) and controls (n = 63) to assess humoral and cellular responses to HBV vaccine provided with three doses under an accelerated schedule of 4 weeks apart. At 1 month post-vaccination all children, except 4 HIV-1 infected, displayed protective antibody (ab) titers to HBV vaccine; ab titers were lower in infected children (P < 0.0001). Ab titers decreased (P < 0.0001) in both HIV-1 infected and control children at 6 months. The frequency of circulating Tfh (cTFh) cells was 20.3% for controls and 20.8% for infected children prior to vaccination and remained comparable post-vaccination. Cytokine expression by cTfh cells upon activation with HBV antigen was comparable in the two groups at baseline and 1 month post-vaccination. Higher plasma levels (P < 0.0001) of CXCL13 were found in infected children which correlated with cTfh cell frequency at baseline. In conclusion, a lower ab response to HBV vaccine was measured in HIV-1 infected children. The frequency and activation profile of cTfh cells was comparable in infected children and controls suggesting that cells other than Tfh cells are responsible for impaired ab response to HBV vaccine.

Hepatitis B virus in drug users in France: prevalence and vaccination history, ANRS-Coquelicot Survey 2011-2013

People who use drugs (PWUD) are a key population for hepatitis B virus (HBV) vaccination and screening. We aimed to estimate the seroprevalence of HBs antigen (HBsAg) and self-reported HBV vaccination history in French PWUD attending harm reduction centres using data from the ANRS-Coquelicot multicentre survey conducted in 2011-2013 in 1718 PWUD. Self-fingerprick blood samples were collected on dried blood spots to detect the presence of HBsAg. HBsAg seroprevalence was estimated at 1·4% [95% confidence interval (CI) 0·8-2·5]. It varied between PWUD born in high (7·6%, 95% CI 2·7-19·1), moderate (2·2%, 95% CI 0·8-5·7) and low (0·7%, 95% CI 0·3-1·5) endemic zones. Factors independently associated with HBsAg carriage were being born in a moderate or high endemic zone or reporting precarious housing. Self-reported HBV vaccination history varied from 47·4% in high endemic zones, to 59·3% and 62·6% for moderate and low endemic zones, respectively. Our results suggest that drug use plays a small and substantial role, respectively, in HBsAg carriage in PWUD born in high/moderate and low endemic zones.

Prevention of transmission of HIV, hepatitis B virus, hepatitis C virus, and tuberculosis in prisoners

The prevalence of HIV, hepatitis B virus, hepatitis C virus, and tuberculosis are higher in prisons than in the general population in most countries worldwide. Prisons have emerged as a risk environment for these infections to be further concentrated, amplified, and then transmitted to the community after prisoners are released. In the absence of alternatives to incarceration, prisons and detention facilities could be leveraged to promote primary and secondary prevention strategies for these infections to improve prisoners health and reduce risk throughout incarceration and on release. Effective treatment of opioid use disorders with opioid agonist therapies (eg, methadone and buprenorphine) prevents blood-borne infections via reductions in injection in prison and after release. However, large gaps exist in the implementation of these strategies across all regions. Collaboration between the criminal justice and public health systems will be required for successful implementation of these strategies.

A Randomized Study Comparing the Efficacy of Three Hepatitis B Vaccine Induction Regimens in Adult Patients with Hematological Malignancies

Objective:

Non-responsiveness to hepatitis B virus (HBV) vaccines is not rare in hemato-oncological patients due to disease-associated or treatment-induced immune suppression. Although different strategies have been employed to improve the response rates, to date there is not an approved schedule for HBV immunization in patients with hematological malignancies. We designed a prospective randomized study to evaluate the efficacy of 3 different induction regimens for HBV vaccination.

Materials and Methods:

In the standard-dose (SD) group, total vaccine dose delivered was 40 µg and patients were vaccinated with 20 µg at weeks 0 and 4. In the high-dose dose-intensive (HDDI) group, total vaccine dose delivered was 80 µg and patients were vaccinated with 40 µg at weeks 0 and 4. In the high-dose time-intensive (HDTI) group, total vaccine dose delivered was 80 µg and patients were vaccinated with 20 µg at weeks 0, 2, 4, and 6.

Results:

In a cohort of 114 patients, 38.6% responded to HBV vaccination. The response rate in the SD arm, HDDI arm, and HDTI arm was 26.2%, 29.7%, and 44.4%, respectively (p>0.05). Age was the only variable identified as having a negative impact on response.

Conclusion:

Short of achieving statistical significance, a higher response rate was observed in the HDTI arm. Therefore, this study supports a high-dose, time-intensive HBV vaccine induction regimen in patients with hematological malignancies who are not on chemotherapy.

Hepatitis Vaccines

Viral hepatitis is a serious health problem all over the world. However, the reduction of the morbidity and mortality due to vaccinations against hepatitis A and hepatitis B has been a major component in the overall reduction in vaccine preventable diseases. We will discuss the epidemiology, vaccine development, and post-vaccination effects of the hepatitis A and B virus. In addition, we discuss attempts to provide hepatitis D vaccine for the 350 million individuals infected with hepatitis B globally. Given the lack of a hepatitis C vaccine, the many challenges facing the production of a hepatitis C vaccine will be shown, along with current and former vaccination trials. As there is no current FDA-approved hepatitis E vaccine, we will present vaccination data that is available in the rest of the world. Finally, we will discuss the existing challenges and questions facing future endeavors for each of the hepatitis viruses, with efforts continuing to focus on dramatically reducing the morbidity and mortality associated with these serious infections of the liver.

Development of immunity following financial incentives for hepatitis B vaccination among people who inject drugs: A randomized controlled trial

BACKGROUND

People who inject drugs (PWID) are at risk of hepatitis B virus (HBV) but have low rates of vaccination completion. The provision of modest financial incentives increases vaccination schedule completion, but their association with serological protection has yet to be determined.

OBJECTIVE

To investigate factors associated with vaccine-induced immunity among a sample of PWID randomly allocated to receive AUD$30 cash following receipt of doses two and three ('incentive condition') or standard care ('control condition') using an accelerated 3-dose (0,7,21 days) HBV vaccination schedule.

STUDY DESIGN

A randomised controlled trial among PWID attending two inner-city health services and a field site in Sydney, Australia, assessing vaccine-induced immunity measured by hepatitis B surface antibodies (HBsAb ≥ 10 mIU/ml) at 12 weeks. The cost of the financial incentives and the provision of the vaccine program are also reported.

RESULTS

Just over three-quarters of participants - 107/139 (77%)--completed the vaccination schedule and 79/139 (57%) were HBsAb ≥ 10 mIU/ml at 12 weeks. Vaccine series completion was the only variable significantly associated with vaccine-induced immunity in univariate analysis (62% vs 41%, p<0.035) but was not significant in multivariate analysis. There was no statistically discernible association between group allocation and series completion (62% vs 53%). The mean costs were AUD$150.5, (95% confidence interval [CI]: 142.7-158.3) and AUD$76.9 (95% CI: 72.6-81.3) for the intervention and control groups respectively.

CONCLUSION

Despite increasing HBV vaccination completion, provision of financial incentives was not associated with enhanced serological protection. Further research into factors which affect response rates and the optimal vaccination regimen and incentive schemes for this population are needed.