Recombinant Hepatitis B Vaccine Adjuvanted With AS04 in Dialysis Patients: A Prospective Cohort Study

Advancements in Vaccine Strategies for Chronic Liver Disease Patients: Navigating Post-COVID Challenges and Opportunities

This review addresses the vital role of vaccinations in managing patients with chronic liver disease (CLD), especially in the context of the post-COVID-19 landscape. The pandemic has highlighted the unique vulnerabilities of CLD patients, including those awaiting liver transplantation and post-transplant individuals, who face heightened risks of infection due to compromised immune responses. Recent advancements in vaccine technology, such as mRNA platforms, novel adjuvants, and advanced delivery systems, have significantly accelerated vaccine development, enhancing both speed and efficacy. Moreover, the emergence of personalized vaccines, tailored to everyone's unique immunological profile, presents new opportunities, particularly for those with chronic conditions. This review synthesizes the current state of evidence regarding vaccine recommendations for CLD patients, focusing on their response to vaccinations and proposing effective strategies to protect this vulnerable group from vaccine-preventable diseases. It also explores the challenges in implementing these strategies and considers the impact of emerging vaccine delivery systems on improving outcomes for CLD patients. The paper aims to provide nuanced guidance on vaccination in the rapidly evolving healthcare landscape, addressing both technological innovations and comprehensive patient care strategies.

TLR agonists as vaccine adjuvants in the prevention of viral infections: an overview

Tol-like receptor (TLR) agonists, as potent adjuvants, have gained attention in vaccine research for their ability to enhance immune responses. This study focuses on their application in improving vaccine efficacy against key viral infections, including hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), SARS-CoV-2, influenza virus, and flaviviruses, including West Nile virus, dengue virus, and chikungunya virus. Vaccines are crucial in preventing microbial infections, including viruses, and adjuvants play a vital role in modulating immune responses. However, there are still many diseases for which effective vaccines are lacking or have limited immune response, posing significant threats to human health. The use of TLR agonists as adjuvants in viral vaccine formulations holds promise in improving vaccine effectiveness. By tailoring adjuvants to specific pathogens, such as HBV, HCV, HIV, SARS-CoV-2, influenza virus, and flavivirus, protective immunity against chronic and emerging infectious disease can be elicited.

Advancements in Vaccine Adjuvants: The Journey from Alum to Nano Formulations

Vaccination is a groundbreaking approach in preventing and controlling infectious diseases. However, the effectiveness of vaccines can be greatly enhanced by the inclusion of adjuvants, which are substances that potentiate and modulate the immune response. This review is based on extensive searches in reputable databases such as Web of Science, PubMed, EMBASE, Scopus, and Google Scholar. The goal of this review is to provide a thorough analysis of the advances in the field of adjuvant research, to trace the evolution, and to understand the effects of the various adjuvants. Historically, alum was the pioneer in the field of adjuvants because it was the first to be approved for use in humans. It served as the foundation for subsequent research and innovation in the field. As science progressed, research shifted to identifying and exploiting the potential of newer adjuvants. One important area of interest is nano formulations. These advanced adjuvants have special properties that can be tailored to enhance the immune response to vaccines. The transition from traditional alum-based adjuvants to nano formulations is indicative of the dynamism and potential of vaccine research. Innovations in adjuvant research, particularly the development of nano formulations, are a promising step toward improving vaccine efficacy and safety. These advances have the potential to redefine the boundaries of vaccination and potentially expand the range of diseases that can be addressed with this approach. There is an optimistic view of the future in which improved vaccine formulations will contribute significantly to improving global health outcomes.

Screening of Efficient Adjuvants for the RBD-Based Subunit Vaccine of SARS-CoV-2

The variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are more transmissible, with a reduced sensitivity to vaccines targeting the original virus strain. Therefore, developing an effective vaccine against both the original SARS-CoV-2 strain and its variants is an urgent need. It is known that the receptor-binding domain (RBD) in the S protein of SARS-CoV-2 is an important vaccine target, but subunit vaccines usually have lower immunogenicity and efficacy. Thus, selecting appropriate adjuvants to enhance the immunogenicity of protein-based subunit vaccine antigens is necessary. Here, an RBD-Fc subunit vaccine of SARS-CoV-2 has been generated, followed by vaccination in B6 mice, and four adjuvant regimens were investigated, including aluminum salts (Alum) + 3-O-desacyl-4'-monophosphoryl lipid A (MPL), AddaVax, QS21 + MPL, and Imiquimod. The adjuvant potency was evaluated by comparing the elicited polyclonal antibodies titers with measuring binding to RBD and S protein in ELISA and Western blot analysis, and also the cross-neutralizing antibodies titers using a pseudovirus infection assay of hACE2-expressing 293T cells, with pseudoviruses expressing the S protein of the SARS-CoV-2 original strain and Delta strain. The presence of QS21 + MPL adjuvant induced stronger polyclonal antibody response and neutralization potency blocking the original strain and Delta strain, as compared with the non-adjuvant RBD-Fc group and other adjuvant groups. Meanwhile, Imiquimod even had a negative effect in inducing specific antibodies and cross-neutralizing antibody production as an adjuvant.

Design, Characterization, and Immune Augmentation of Docosahexaenoic Acid Nanovesicles as a Potential Delivery System for Recombinant HBsAg Protein

Recombinant HBsAg-loaded docosahexaenoic acid nanovesicles were successfully developed, lyophilized (LRPDNV) and characterized for their physico-chemical properties. The zetapotential (ZP) of LRPDNV was −60.4 ± 10.4 mV, and its polydispersity (PDI) was 0.201, with a % PDI of 74.8. The particle sizes of LRPDNV were 361.4 ± 48.24 z. d.nm and 298.8 ± 13.4 r.nm. The % mass (r.nm) of LRPDNV in a colloidal injectable system was 50, its mobility value was −3.417 µm cm/Vs, while the conductivity of the particles was 0.728 (mS/cm). Transmission electron microscopic (TEM) analysis showed smooth morphological characteristics of discrete spherical LRPDNV. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of LRPDNV revealed that LRPDNV is thermostable. The X-ray diffraction (XRD) studies showed a discrete crystalline structure of LRPDNV at 2θ. Nuclear magnet resonance (NMR) studies (1H-NMR and 13C-NMR spectrum showed the discrete structure of LRPDNV. The immunogenicity study was performed by antibody induction technique. The anti-HBs IgG levels were elevated in Wistar rats; the antibody induction was observed more in the product (LRPDNV) treatment group when compared to the standard vaccine group. The level of antibodies on the 14th and 30th day was 6.3 ± 0.78 U/mL and 9.24 ± 1.76 U/mL in the treatment and standard vaccine groups, respectively. Furthermore, the antibody level on the 30th day in the treatment group was 26.66 ± 0.77 U/mL, and in the standard vaccine group, the antibody level was 23.94 ± 1.62 U/mL. The LRPDNV vaccine delivery method released HBsAg sustainably from the 14th to the 30th day. The results of this study indicate the successful formulation of DHA nanovesicles which have great potential as an adjuvant system for the delivery of recombinant HBsAg protein.

A Double-blind, Randomized Phase 2 Controlled Trial of Intradermal Hepatitis B Vaccination With a Topical Toll-like Receptor 7 Agonist Imiquimod, in Patients on Dialysis

BACKGROUND

Patients on dialysis are hyporesponsive to the hepatitis B virus vaccines (HBVv). We examined intradermal (ID) HBVv Sci-B-Vac, with topical Toll-like receptor 7 (TLR7) agonist imiquimod pretreatment in dialysis patients.

METHODS

We enrolled and prospectively followed adult patients on dialysis between January 2016 and September 2018. Eligible patients were randomly allocated (1:1:1) into 1 treatment group, topical imiquimod cream followed by ID HBVv (IMQ + ID); and 2 control groups: topical aqueous cream (placebo) followed by ID HBVv (AQ + ID) or topical aqueous cream followed by intramuscular HBVv (AQ + IM). The primary endpoint was the seroprotection rate (hepatitis B surface antibody ≥10 mIU/mL) at 52 weeks.

RESULTS

Ninety-four patients were enrolled, among which 57.4% were previous nonresponders. Seroprotection rate was significantly better at week 52 for the IMQ + ID group with 96.9% compared to 74.2% and 48.4% for AQ + ID and AQ + IM groups, respectively (P < .0001). The geometric mean concentration was significantly higher at week 52 for the IMQ + ID group: 1135 (95% confidence interval [CI], 579.4-2218.2) mIU/mL, compared to 86.9 (95% CI, 18.5-409.3) mIU/mL and 7.2 (2.0-26.5) mIU/mL for the AQ + ID and AQ + IM groups, respectively (P < .0001). IMQ + ID vaccination (odds ratio, 3.70 [95% CI, 1.16-11.81]; P = .027) was the only factor independently associated with higher 52-week seroprotection rate. Adverse reaction was infrequent.

CONCLUSIONS

Pretreatment with topical imiquimod before ID HBVv Sci-B-Vac was safe with favorable seroprotection in dialysis patients.

CLINICAL TRIALS REGISTRATION

NCT02621112.

Hepatitis B virus vaccine and chronic kidney disease. The advances

BACKGROUND

Hepatitis B is an important agent of liver disease in patients with chronic kidney disease and chronic HBV infection promotes the development of CKD in the adult general population. Patients with CKD have a suboptimal response to various vaccines, and it remains unclear how we boost the immune response of CKD patients to HB vaccine.

STUDY AIMS AND DESIGN

We performed a narrative review to assess the mechanisms of lower immunogenicity of HBV vaccine in CKD population; multiple approaches to improve the response rate of CKD patients to HBV vaccine have been reported. This is a very important topic for nephrologists who often serve as primary case providers for patients with CKD.

RESULTS

The recommended vaccine schedule for CKD patients including those on maintenance dialysis is based on recombinant vaccine, four doses (month 0,1,2, and 6; 40mcg each) by intramuscular route (deltoid muscle). According to RCTs or observational studies, some recombinant vaccines with adjuvants (i.e., HBV-AS02 and HBV-AS04) look promising. HBV-AS04 showed to give better seroprotection rates and durable immune response over extended follow-ups compared with licensed HBV vaccine in CKD patients. The seroprotection rate was 95% (97/102) and 82% (202/248) in pre-dialysis and dialysis patients, respectively, one month after completing vaccine schedule with HBV-AS04. HBV-AS02 was superior to licensed vaccine in terms of seroprotection rate, 76.9% vs. 37.6%.

CONCLUSIONS

We suggest adjuvanted recombinant (HBV-AS04) vaccine (0,1,2 and 3 months; 20 mcg each dose) and post vaccination testing of anti-HBs antibody after vaccination. Booster doses to patients whose anti-HBs titers fall below the seroprotection level (<10IU/mL) during the follow-up are appropriate. The patho-physiologic mechanisms responsible for the poor immunogenicity of HBV vaccine in CKD patients are under active investigation.

Hepatitis B virus vaccine and chronic kidney disease. The advances

BACKGROUND

Hepatitis B is an important agent of liver disease in patients with chronic kidney disease and chronic HBV infection promotes the development of CKD in the adult general population. Patients with CKD have a suboptimal response to various vaccines, and it remains unclear how we boost the immune response of CKD patients to HB vaccine.

STUDY AIMS AND DESIGN

We performed a narrative review to assess the mechanisms of lower immunogenicity of HBV vaccine in CKD population; multiple approaches to improve the response rate of CKD patients to HBV vaccine have been reported. This is a very important topic for nephrologists who often serve as primary case providers for patients with CKD.

RESULTS

The recommended vaccine schedule for CKD patients including those on maintenance dialysis is based on recombinant vaccine, four doses (month 0,1,2, and 6; 40mcg each) by intramuscular route (deltoid muscle). According to RCTs or observational studies, some recombinant vaccines with adjuvants (i.e., HBV-AS02 and HBV-AS04) look promising. HBV-AS04 showed to give better seroprotection rates and durable immune response over extended follow-ups compared with licensed HBV vaccine in CKD patients. The seroprotection rate was 95% (97/102) and 82% (202/248) in pre-dialysis and dialysis patients, respectively, one month after completing vaccine schedule with HBV-AS04. HBV-AS02 was superior to licensed vaccine in terms of seroprotection rate, 76.9% vs. 37.6%.

CONCLUSIONS

We suggest adjuvanted recombinant (HBV-AS04) vaccine (0,1,2 and 3 months; 20 mcg each dose) and post vaccination testing of anti-HBs antibody after vaccination. Booster doses to patients whose anti-HBs titers fall below the seroprotection level (<10IU/mL) during the follow-up are appropriate. The patho-physiologic mechanisms responsible for the poor immunogenicity of HBV vaccine in CKD patients are under active investigation.

PEGylated single-walled carbon nanotubes as co-adjuvants enhance expression of maturation markers in monocyte-derived dendritic cells

Aim: This study investigated the application of phospholipid-PEGylated single-walled carbon nanotubes (PL-PEG-SWCNTs) as a safe co-adjuvant for the commercial recombinant hepatitis B virus vaccine to enhance induction of monocyte-derived dendritic cells (MDDCs) differentiation and activation in vitro as an immune response initiator cell to prompt a long-term immune response after a single dose injection. Methods: Immature MDDCs were exposed to PL-PEG-SWCNTs alone and in combination with hepatitis B vaccine. Results & conclusion: Study results confirm the enhanced expression of maturation markers in human immature MDDCs after PL-PEG-SWCNT exposure. The results suggest that PL-PEG-SWCNT is an efficient co-adjuvant for the commercial recombinant hepatitis B virus vaccine to enhance dendritic cell response stimulation in vitro.

Adjuvanted recombinant HBV vaccine (HBV-AS04) is effective over extended follow-up in dialysis population. An open-label non randomized trial

BACKGROUND

Patients on regular dialysis show a poor response to hepatitis B vaccine due to uremia. A recombinant HB vaccine (containing an improved adjuvant system AS04, HBV-AS04) has been licensed but the evidence on its efficacy and safety in dialysis population over the long term is extremely limited.

AIM

We have measured antibody (anti-HBs) persistence for up to 72 months in a large cohort of patients on long-term dialysis (with susceptibility to HBV infection) who underwent vaccination with HBV-AS04 vaccine.

METHODS

Patients were prospectively recruited to receive four 20-mcg doses of HBV-AS04 by intramuscular route (deltoid muscle). Two vaccine schedules were adopted: 0,1,2, and 3 month (n=217 patients) and 0,1,2, and 6 month (n=31 patients). Anti-HBs antibody concentrations were tested at 1,2,3, 4, 7 and 12 months and then every year up to 72 months. Multivariate analysis was made to find the baseline parameters that were associated with the immune response to HBV-AS04 vaccine.

RESULTS

Two hundred and seventy-two patients were included and 248 completed the study. At completion of vaccine schedule, the frequency of responders (anti-HBs titers≥10mIU/mL) was 81.5% (202/248) (mean anti-HBs antibody titers, 384.9±391.9mIU/mL), according to per-protocol analysis. On the grounds of univariate analysis, age was lower in responder than non- responder patients to HBV AS04 even if no statistical significance was achieved (P=0.09). The sero-protection rate at month 72 was 77% (7/9) (anti-HBs antibody titers, 184.9±360.1mIU/mL, P=0.001). Multivariate analysis found a relationship between sero-response rate and age (P=0.04). No major side effects and no de novo HBV episodes were observed.

CONCLUSIONS

Our open-label nonrandomized trial performed in a 'real-world' practice showed the persistence of anti-HBs antibody among responder patients over a very long follow-up. Studies with longer observation periods are under way.

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.

Risk factors of the efficacy of hepatitis B vaccine in health-care workers

Background

Conventional hepatitis B virus vaccination fails to achieve efficient protection in about 5%-10% of the world population. Different factors influence the immunogenicity of hepatitis B vaccine. This study aimed to evaluate these factors in health-care workers.

Materials and Methods

This was a descriptive study which was implemented among 140 of medical and dental staff working as health-care workers who were low responder after vaccination entered the study.

Results

Age (>40 years), weight (body mass index >25), immunodeficiency diseases, (primary immune deficiency and immunosuppressant drugs), diabetes mellitus, and smoking were the important factors.

Conclusion

In the high-risk group of hepatitis B disease, the risk factors of immunogenicity must be evaluated at vaccination and check titers of antibody after vaccination.

Toward precision adjuvants: optimizing science and safety

PURPOSE OF REVIEW

The gradual replacement of inactivated whole cell and live attenuated vaccines with subunit vaccines has generally reduced reactogenicity but in many cases also immunogenicity. Although only used when necessary, adjuvants can be key to vaccine dose/antigen-sparing, broadening immune responses to variable antigens, and enhancing immunogenicity in vulnerable populations with distinct immunity. Licensed vaccines contain an increasing variety of adjuvants, with a growing pipeline of adjuvanted vaccines under development.

RECENT FINDINGS

Most adjuvants, including Alum, Toll-like receptor agonists and oil-in-water emulsions, activate innate immunity thereby altering the quantity and quality of an adaptive immune response. Adjuvants activate leukocytes, and induce mediators (e.g., cytokines, chemokines, and prostaglandin-E2) some of which are biomarkers for reactogenicity, that is, induction of local/systemic side effects. Although there have been safety concerns regarding a hypothetical risk of adjuvants inducing auto-immunity, such associations have not been established. As immune responses vary by population (e.g., age and sex), adjuvant research now incorporates principles of precision medicine. Innovations in adjuvant research include use of human in vitro models, immuno-engineering, novel delivery systems, and systems biology to identify biomarkers of safety and adjuvanticity.

SUMMARY

Adjuvants enhance vaccine immunogenicity and can be associated with reactogenicity. Novel multidisciplinary approaches hold promise to accelerate and de-risk targeted adjuvant discovery and development. VIDEO ABSTRACT: http://links.lww.com/MOP/A53.

HBV vaccination with Fendrix is effective and safe in pre-dialysis CKD population

BACKGROUND

Patients with chronic kidney disease have a poor response to hepatitis B vaccine due to the immunodeficiency conferred from chronic uremia. A recombinant HB vaccine containing an improved adjuvant system AS04 (HBV-AS04) has been manufactured but scarce evidence exists on HBV-AS04 use among patients with CKD.

AIM

To assess efficacy and safety of an adjuvanted recombinant vaccine (HBV-AS04) in a large cohort of CKD patients at pre-dialysis stage (with susceptibility to HBV infection).

METHODS

Patients were prospectively enrolled to receive four 20-mcg doses of HBV-AS04 by intramuscular route (deltoid muscle) at months 1, 2, 3, and 4. Anti-HBs surface antibody concentrations were tested at intervals of 1, 2, 3, 4, and 12months. Multivariate analyses were performed to assess the parameters, which predicted immunologic response to HBV-AS04 vaccine.

RESULTS

One hundred and seven patients were included and 102 completed the study. At completion of vaccine schedule, the frequency of responders (anti-HBs titers≥10mIU/mL) was 95% (97/102) (mean anti-HBs antibody titers, 688.9±385mIU/mL), according to per-protocol analysis. Serum haemoglobin levels were greater in responder than non- or low-responder patients to HBV-AS04 (P=0.04) and this was confirmed by multivariate analysis. The seroprotection rate at month 50 was 88% (30/34) with lower anti-HBs antibody titers (218.5±269.6mIU/mL, P=0.001). No major side effects were observed.

CONCLUSIONS

Our prospective study performed in a real-world setting showed a high immunogenicity and safety of HBV-AS04 vaccine in patients with CKD not yet on maintenance dialysis. Studies provided with longer follow-ups are under way to assess the durability of seroprotection in responders.

Vaccination practices in dialysis patients: A narrative review

In a period of turmoil concerning vaccination practices, there is a serious conflict between scientifically reasonable, evidence-based guidelines and the far-fetched rumors or misconceptions concerning the vaccination practices in the general population. When a significant portion of the medical and paramedical personnel may be deliberately unvaccinated against common biological agents, achieving effective vaccination rates in the dialysis population may be complicated. Vaccination rates are unacceptably low in dialysis patients and seroconversion rates are even lower; further, serological follow-up is generally poor. The particularly anergic immune system of the advanced chronic kidney disease patients is partly a cause of both high rates of infection and low rates of seroconversions. This narrative review is an effort to summarize current knowledge concerning the vaccination practices in dialysis patients with some specific recommendations based on these facts. Of particular interest is a new vaccine, the Zoster Recombinant, Adjuvanted Vaccine (Shingrix), which we will include in our discussion.

A randomized, controlled clinical trial to evaluate the immunogenicity of a PreS/S hepatitis B vaccine Sci-B-Vac™, as compared to Engerix B®, among vaccine naïve and vaccine non-responder dialysis patients

BACKGROUND

Dialysis patients have a suboptimal response to hepatitis B (HBV) vaccination. This study aimed to compare the immunogenicity of two vaccines: the third-generation Sci-B-Vac™ vs. the second-generation Engerix B^®. The cohort included two groups of dialysis patients: naïve and previously vaccinated non-responders. Primary endpoints were antibody titers ≥10 IU/L at 3 and 7 month post-vaccination. Secondary objectives were seroprotection rates in vaccine-naïve patients and in previously vaccinated non-responders.

METHODS

Eighty-six patients were assigned to vaccine (Sci-B-Vac™ or Engerix B^®) using computer-generated randomization, stratified by age, gender, diabetes, and previous HBV vaccination. Sci-B-Vac™ was administered in three doses, 10 μg, at 0, 1, and 6 months in naïve patients; or 20 μg in previously vaccinated non-responders. Engerix B^® included four doses, 40 μg at 0, 1, 2, and 6 months.

RESULTS

Each group had 43 patients. Seroconversion was 69.8% with Engerix B^® vs. 73.2% with Sci-B-Vac™. Antibody titers at 7 months were higher with Sci-B-Vac™ (266.4 ± 383.9, median 53.4) than with Engerix^® (193.2 ± 328.9, median 19). However, these differences were not significant, perhaps due to a suboptimal sample size.

CONCLUSIONS

This study suggests comparable immunogenicity for both vaccines. Thus, we cannot reject the null hypothesis that there is no difference in seroconversion by vaccine type. It is noteworthy that naïve patients were vaccinated with a standard dose of Sci-B-Vac™, while Engerix B^® was administered at a double dose. Similarly, although mean antibody titer levels in the Sci-B-Vac™ group were higher than in the Engerix^® group, this difference did not reach significance. Consequently, a future clinical trial should recruit a larger cohort of patients, using a standard double-dose protocol in both groups.

Vaccination against hepatitis B virus among people who inject drugs - A 20year experience from a Swedish needle exchange program

BACKGROUND

People who inject drugs (PWID) are at particular risk of hepatitis B virus (HBV) acquisition, but often have poor access or adherence to HBV vaccination. Vaccination against HBV has been offered at a major Swedish needle exchange program (NEP) since 1994. The aim of this study was to evaluate vaccine completion and response rates, and the effect of sequential booster doses to non-responders to the standard vaccination schedule.

METHODS

PWID enrolled in the NEP 1994-2013, without serological markers for HBV at baseline (negative for HBsAg/anti-HBc/anti-HBs), were offered a three-dose standard intramuscular vaccination schedule (Engerix®-B, GSK, 20μg/mL, intended to be received at months 0, 1 and 6). Vaccination response was defined as protective levels of anti-HBs (⩾10mIU/mL). Up to three booster doses were then offered for non-responders, each followed by anti-HBs testing.

RESULTS

HBV data was available for 2352 identifiable individuals at NEP enrolment, of whom 1516 (64.5%) had no markers for previous HBV exposure or vaccination. Vaccination was initiated for 1142 (75.3%) individuals and 898 (59.2%) completed the standard vaccination schedule. Post-vaccination anti-HBs levels were available from 800 individuals, with 598 (74.8%) responding to the basic vaccination schedule. After up to three booster doses a total of 676 (84.5%) individuals achieved protective anti-HBs levels. Non-response to vaccination was associated with higher age and anti-HCV positivity (p<0.001). Eighteen incident cases of HBV infection were observed among vaccine non-responders, as well as 30 cases among those who had not completed vaccination.

CONCLUSION

We demonstrate the feasibility of including HBV vaccination in the services offered by a NEP, with completion of vaccination in a majority of HBV-susceptible PWID. The response to HBV vaccination among PWID was relatively low; however, the addition of up to three booster doses improved the response rate from 74.8 to 84.5%.