Comparison of higher-dose intradermal hepatitis B vaccination to standard intramuscular vaccination of healthcare workers

Dual pattern recognition receptor ligands CL401, CL413, and CL429 as adjuvants for inactivated chikungunya virus

Chikungunya virus (CHIKV) is responsible for incapacitating joint pains and is a significant health hazard in many countries. Though a definite need for a CHIKV vaccine is felt, long disappearance of CHIKV from circulation in humans has been a concern for vaccine development. Use of two separate pattern recognition receptor ligands has been shown to enhance immune response to the administered antigen. In addition, intradermal delivery of vaccine tends to mimic the natural mode of CHIKV infection. Therefore, in this study, we explored whether intradermal and intramuscular immunization with inactivated CHIKV (I-CHIKV) supplemented with dual pattern-recognition receptor ligands, CL401, CL413, and CL429, is an effective approach to enhancing antibody response to CHIKV. Our in vivo data show that I-CHIKV supplemented with these chimeric PRR ligands induces enhanced neutralizing antibody response after intradermal delivery, but is less efficient after intramuscular immunization. These results suggest that intradermal delivery of I-CHIKV with chimeric adjuvants is a possible way to elicited a better antibody response.

Successful response of intradermal hepatitis B vaccine in nonresponders of intramuscular hepatitis B vaccine in general and hemodialysis population

BACKGROUND

Hepatitis B infection is one of the most common infections worldwide, with its vaccination being an effective preventive measure. Nonresponse to hepatitis B vaccination increases population susceptibility to virus dissemination along with detrimental complications. Despite twice intramuscular vaccination series, 14.3% in the general population and 50% in hemodialysis patients fail to mount a response against hepatitis B. We aimed to evaluate the effectiveness of intradermal (ID) vaccination in the nonresponders amongst the general and hemodialysis population.

METHODS

A total of 5 doses of 10 μg of hepatitis B vaccine was given intradermally, 2 weeks apart, to both the study groups: patients who were on hemodialysis and the general population group who previously had failed to achieve satisfactory antibody titers with the IM administration of the vaccine. A hepatitis B surface antibody (HBsAb) titer of ≥10 IU/mL and ≥100 IU/mL were considered "responder" and "good responder," respectively.

RESULTS

Out of a total of 95 participants, 49 (51.6%) were hemodialysis-dependent. Most of the participants were females 49 (51.6%). The mean age of all the participants was 39.02 ± 13.5 years (range: 18-70 years). Overall, 75.8% of the participants responded to the ID vaccination with a mean HBsAb titer of 263.5 ± 350.1 IU/L. Almost similar vaccination response was observed in both the hemodialysis and general population i.e., 75.5% and 76.1%, respectively (P = 1.00). In the hemodialysis group, the absence of hypertension (P = 0.04) and age ≥36 years (P = 0.016) were associated with an ID vaccination response.

CONCLUSION

For those not responding to the conventional IM route of the hepatitis B vaccine, the ID route is an effective way of immunization in this group and this approach would lead to a decrease in infection rates in the vulnerable population such as those on hemodialysis.

Fractional dose of intradermal compared to intramuscular and subcutaneous vaccination - A systematic review and meta-analysis

BACKGROUND

Vaccine supply shortages are of global concern. We hypothesise that intradermal (ID) immunisation as an alternative to standard routes might augment vaccine supply utilisation without loss of vaccine immunogenicity and efficacy.

METHODS

We conducted a systematic review and meta-analysis searching Medline, Embase and Web of Science databases. Studies were included if: licensed, currently available vaccines were used; fractional dose of ID was compared to IM or SC immunisation; primary immunisation schedules were evaluated; immunogenicity, safety data and/or cost were reported. We calculated risk differences (RD). Studies were included in meta-analysis if: a pre-defined immune correlate of protection was assessed; WHO-recommend schedules and antigen doses were used in the control group; the same schedule was applied to both ID and control groups (PROSPERO registration no. CRD42020151725).

RESULTS

The primary search yielded 5,873 articles, of which 156 articles were included; covering 12 vaccines. Non-inferiority of immunogenicity with 20-60% of antigen used with ID vaccines was demonstrated for influenza (H1N1: RD -0·01; 95% CI -0·02, 0·01; I² = 55%, H2N3: RD 0·00; 95% CI -0·01, 0·01; I² = 0%, B: RD -0·00; 95% CI -0·02, 0·01; I² = 72%), rabies (RD 0·00; 95% CI -0·02, 0·02; I² = 0%), and hepatitis B vaccines (RD -0·01; 95% CI -0·04, 0·02; I² = 20%). Clinical trials on the remaining vaccines yielded promising results, but are scarce.

CONCLUSIONS

There is potential for inoculum/antigen dose-reduction by using ID immunisation as compared to standard routes of administration for some vaccines (e.g. influenza, rabies). When suitable, vaccine trials should include an ID arm.

A grading system for local skin reactions developed for clinical trials of an intradermal and transcutaneous ETEC vaccine

BACKGROUND

Trials assessing the safety of novel vaccine candidates are essential in the evaluation and development of candidate vaccines. Immunogenicity and dose-sparing features of vaccination approaches which target skin and associated tissues have garnered increased interest; for enteric vaccines, cutaneous vaccination has been of particular interest. Cutaneous vaccine site reactions are among the most common and visible vaccine related adverse events (AEs) when skin routes are used. Regulatory guidelines governing classification of severity focus on functional impact but are insufficient to characterize a spectrum of skin reaction and allow for comparisons of routes, doses and products with similar local cutaneous AEs.

OBJECTIVES

Our group developed a grading scale to evaluate and compare cutaneous vaccine site reactions ahead of early-phase clinical trials of intradermal (ID) and transcutaneous immunization (TCI) with enterotoxigenic E.coli (ETEC) vaccine candidates (adhesin-based vaccine co-administered with LTR192G). We reviewed existing methods for characterizing the appearance and severity of local vaccine site reactions following TCI and ID vaccination and devised a standardized vaccine site appearance grading scale (VSAGS) for use in the clinical development of novel ETEC vaccine candidates which focused on pathophysiologic manifestation of skin findings.

RESULTS

Available data from published reports revealed erythematous papules and pruritus were the most common local AEs associated with TCI. Frequency of reactions varied notably across studies as did TCI vaccination methodologies and products. ID vaccination commonly results in erythema and induration at the vaccine site as well as pigmentation changes. There was no published methodology to characterize the spectrum of dermatologic findings.

CONCLUSION

ID and TCI vaccination are associated with a largely predictable range of cutaneous AEs. A grading scale focused on the appearance of cutaneous changes was useful in comparing cutaneous AEs. A standardized grading scale will facilitate documentation and comparison of cutaneous AEs.

Pre-clinical evaluation of a quadrivalent HCV VLP vaccine in pigs following microneedle delivery

The introduction of directly acting antiviral agents (DAAs) has produced significant improvements in the ability to cure chronic hepatitis C infection. However, with over 2% of the world’s population infected with HCV, complications arising from the development of cirrhosis of the liver, chronic hepatitis C infection remains the leading indication for liver transplantation. Several modelling studies have indicated that DAAs alone will not be sufficient to eliminate HCV, but if combined with an effective vaccine this regimen would provide a significant advance towards achieving this critical World Health Organisation goal. We have previously generated a genotype 1a, 1b, 2a, 3a HCV virus like particle (VLP) quadrivalent vaccine. The HCV VLPs contain the core and envelope proteins (E1 and E2) of HCV and the vaccine has been shown to produce broad humoral and T cell immune responses following vaccination of mice. In this report we further advanced this work by investigating vaccine responses in a large animal model. We demonstrate that intradermal microneedle vaccination of pigs with our quadrivalent HCV VLP based vaccine produces long-lived multi-genotype specific and neutralizing antibody (NAb) responses together with strong T cell and granzyme B responses and normal Th1 and Th2 cytokine responses. These responses were achieved without the addition of adjuvant. Our study demonstrates that our vaccine is able to produce broad immune responses in a large animal that, next to primates, is the closest animal model to humans. Our results are important as they show that the vaccine can produce robust immune responses in a large animal model before progressing the vaccine to human trials.

Hepatitis C Virus Infection: Host⁻Virus Interaction and Mechanisms of Viral Persistence

Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host-HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host-HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence.

ZnO Nano-Rod Devices for Intradermal Delivery and Immunization

Intradermal delivery of antigens for vaccination is a very attractive approach since the skin provides a rich network of antigen presenting cells, which aid in stimulating an immune response. Numerous intradermal techniques have been developed to enhance penetration across the skin. However, these methods are invasive and/or affect the skin integrity. Hence, our group has devised zinc oxide (ZnO) nano-rods for non-destructive drug delivery. Chemical vapour deposition was used to fabricate aligned nano-rods on ZnO pre-coated silicon chips. The nano-rods’ length and diameter were found to depend on the temperature, time, quality of sputtered silicon chips, etc. Vertically aligned ZnO nano-rods with lengths of 30–35 µm and diameters of 200–300 nm were selected for in vitro human skin permeation studies using Franz cells with Albumin-fluorescein isothiocyanate (FITC) absorbed on the nano-rods. Fluorescence and confocal studies on the skin samples showed FITC penetration through the skin along the channels formed by the nano-rods. Bradford protein assay on the collected fluid samples indicated a significant quantity of Albumin-FITC in the first 12 h. Low antibody titres were observed with immunisation on Balb/c mice with ovalbumin (OVA) antigen coated on the nano-rod chips. Nonetheless, due to the reduced dimensions of the nano-rods, our device offers the additional advantage of excluding the simultaneous entrance of microbial pathogens. Taken together, these results showed that ZnO nano-rods hold the potential for a safe, non-invasive, and painless intradermal drug delivery.

Comparison of lyophilized versus liquid modified vaccinia Ankara (MVA) formulations and subcutaneous versus intradermal routes of administration in healthy vaccinia-naïve subjects

Background

Modified vaccinia Ankara (MVA) is being developed as a safer smallpox vaccine and is being placed in the US Strategic National Stockpile (SNS) as a liquid formulation for subcutaneous (SC) administration at a dose of 1 × 10⁸ TCID₅₀ in a volume of 0.5 mL. This study compared the safety and immunogenicity of the standard formulation, dose and route with both a more stable, lyophilized formulation and with an antigen-sparing intradermal (ID) route of administration.

Methods

524 subjects were randomized to receive either a full dose of Lyophilized-SC, a full dose of Liquid-SC or 20% (2 × 10⁷ TCID₅₀ in 0.1 mL) of a full dose Liquid-ID MVA on Days 0 and 28. Safety and immunogenicity were followed through 180 days post second vaccination.

Results

Among the 3 groups, the proportion of subjects with moderate/severe functional local reactions was significantly different (P = 0.0013) between the Lyophilized-SC group (30.3%), the Liquid-SC group (13.8%) and Liquid-ID group (22.0%) only after first vaccination; and for moderate/severe measured erythema and/or induration after any vaccination (P = 0.0001) between the Lyophilized-SC group (58.2%), the Liquid-SC group (58.1%) and the Liquid-ID group (94.8%) and the reactions lasted longer in the Liquid-ID group. In the ID Group, 36.1% of subjects had mild injection site skin discoloration lasting ≥6 months.

After second vaccination Day (42–208), geometric mean of peak neutralization titers were 87.8, 49.5 and 59.5 for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively, and the maximum number of responders based on peak titer in each group was 142/145 (97.9%), 142/149 (95.3%) and 138/146 (94.5%), respectively. At 180 days after the second vaccination, geometric mean neutralization titers declined to 11.7, 10.2 and 10.4 with only 54.3%, 39.2% and 35.2% of subjects remaining seropositive for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively. Both the Lyophilized-SC and Liquid-ID groups were considered non-inferior (primary objective) to the Liquid-SC group.

Conclusions

Transitioning to a lyophilized formulation, which has a longer shelf life, will not negatively impact immunogenicity. In a situation where insufficient vaccine is available, ID vaccination could be used, increasing the number of available doses of vaccine in the SNS 5-fold (i.e., from 20 million to 100 million doses).

Intradermal immunization triggers epidermal Langerhans cell mobilization required for CD8 T-cell immune responses

The potential of the skin immune system for the generation of both powerful humoral and cellular immune responses is now well established. However, the mechanisms responsible for the efficacy of skin antigen-presenting cells (APCs) during intradermal (ID) vaccination still remain to be elucidated. We have previously demonstrated in clinical trials that preferential targeting of Langerhans cells (LCs) by transcutaneous immunization shapes the immune response toward vaccine-specific CD8 T cells. Others have shown that ID inoculation of a vaccine, which targets dermal APCs, mobilizes both the cellular and humoral arms of immunity. Here, we investigated the participation of epidermal LCs in response to ID immunization. When human or mouse skin was injected ID with a particle-based vaccine, we observed significant modifications in the morphology of epidermal LCs and their mobilization to the dermis. We further established that this LC recruitment after ID administration was essential for the induction of antigen-specific CD8 T cells, but was, however, dispensable for the generation of specific CD4 T cells and neutralizing antibodies. Thus, epidermal and dermal APCs shape the outcome of the immune responses to ID vaccination. Their combined potential provides new avenues for the development of vaccination strategies against infectious diseases.

Safety and immunogenicity of an HIV adenoviral vector boost after DNA plasmid vaccine prime by route of administration: a randomized clinical trial

BACKGROUND

In the development of HIV vaccines, improving immunogenicity while maintaining safety is critical. Route of administration can be an important factor.

METHODOLOGY/PRINCIPAL FINDINGS

This multicenter, open-label, randomized trial, HVTN 069, compared routes of administration on safety and immunogenicity of a DNA vaccine prime given intramuscularly at 0, 1 and 2 months and a recombinant replication-defective adenovirus type 5 (rAd5) vaccine boost given at 6 months by intramuscular (IM), intradermal (ID), or subcutaneous (SC) route. Randomization was computer-generated by a central data management center; participants and staff were not blinded to group assignment. The outcomes were vaccine reactogenicity and humoral and cellular immunogenicity. Ninety healthy, HIV-1 uninfected adults in the US and Peru, aged 18-50 were enrolled and randomized. Due to the results of the Step Study, injections with rAd5 vaccine were halted; thus 61 received the booster dose of rAd5 vaccine (IM: 20; ID:21; SC:20). After the rAd5 boost, significant differences by study arm were found in severity of headache, pain and erythema/induration. Immune responses (binding and neutralizing antibodies, IFN-γ ELISpot HIV-specific responses and CD4+ and CD8+ T-cell responses by ICS) at four weeks after the rAd5 booster were not significantly different by administration route of the rAd5 vaccine boost (Binding antibody responses: IM: 66.7%; ID: 70.0%; SC: 77.8%; neutralizing antibody responses: IM: 11.1%; ID: 0.0%; SC 16.7%; ELISpot responses: IM: 46.7%; ID: 35.3%; SC: 44.4%; CD4+ T-cell responses: IM: 29.4%; ID: 20.0%; SC: 35.3%; CD8+ T-cell responses: IM: 29.4%; ID: 16.7%; SC: 50.0%.)

CONCLUSIONS/SIGNIFICANCE

This study was limited by the reduced sample size. The higher frequency of local reactions after ID and SC administration and the lack of sufficient evidence to show that there were any differences in immunogenicity by route of administration do not support changing route of administration for the rAd5 boost.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00384787.

Intradermal hepatitis B vaccination in non-responders after topical application of imiquimod (Aldara)

BACKGROUND

Five to ten percent of immunocompetent persons fail to develop a protective immune response to hepatitis B vaccination, and are defined non-responders (NR). We investigated the immune response to intradermal hepatitis B vaccination after pre-treatment of the skin with the TLR7 agonist imiquimod.

METHODS

Twenty-one non-responders (anti-HBs <10 IU/l after at least 6 intramuscular hepatitis B vaccinations) were randomly assigned to the control group (N=11) or the experimental group (N=10). Participants in both groups received 3 intradermal (ID) vaccinations with 5 microg HBsAg (0.125 mL) at 0, 1 and 6 months. In the experimental group, the dermal site of injection was pre-treated with 250 mg imiquimod ointment. Anti-HBs antibodies were determined at 0, 1, 2, 6 and 7 months.

RESULTS

In both study groups, 70% of the participants developed a protective immune response (anti-HBs >or=10 IU/l), after the 3rd intradermal vaccination.

CONCLUSION

The application of imiquimod on the skin prior to intradermal vaccination did not enhance the humoral response to hepatitis B vaccine. However, irrespective of imiquimod application, 70% of the NR who had not responded to 6 previous intramuscular vaccinations, developed a protective immune response with high affinity antibodies after 3 ID hepatitis B vaccinations with 5 microg HBsAg.

Cutaneous delivery of prophylactic and therapeutic vaccines: historical perspective and future outlook

The skin has long been recognized as an attractive target for vaccine administration. A number of clinical studies have tested the epidermal and dermal routes of delivery using a variety of vaccines over the years. In many cases, cutaneous administration has been associated with immunological benefits, such as the induction of greater immune responses compared with those elicited by conventional routes of delivery. Furthermore, there is a growing body of evidence to suggest that such benefits may be particularly important for certain higher-risk populations, such as the elderly, the immunocompromised and cancer patients. Despite the potential advantages of vaccination via the skin, results have sometimes been conflicting and the full benefits of this approach have not been fully realized, partly due to the lack of delivery devices that accurately and reproducibly administer vaccines to the skin. The 5-year outlook, however, appears quite promising as new cutaneous delivery systems advance through clinical trials and become available for more widespread clinical and commercial use.

Intradermal, epidermal and transcutaneous vaccination: from immunology to clinical practice

The dermis and epidermis are alternative sites for prophylactic vaccination that have received renewed interest in recent years, not only because of the ease of access to the skin, but also its unique immunological properties. This review discusses the characteristics of the skin, current knowledge on skin immunity and clinical experience with cutaneous immunization against infectious diseases, with a special focus on intradermal immunization. The most widely accepted paradigm explaining the efficacy of cutaneous immunization is reviewed and recent research suggesting where this paradigm may need some refinement is highlighted. Clinical investigations that have concentrated on the intradermal route to vaccinate against influenza, rabies or hepatitis B support the current knowledge on skin immunity and, when combined with recent progress made in the development of user-friendly injection systems, have stimulated the ongoing clinical development of novel vaccines.

Specific immunization issues in the occupational health setting

This article looks at the components of an effective occupational health vaccination programme and also reviews the legal basis for them. It addresses the issue of vaccine licensing including pre-clinical, clinical and post-licensing studies. It explores screening for vaccine preventable diseases in the occupational health setting and then addresses particular issues around hepatitis B, chicken pox, tuberculosis, measles, rubella, diphtheria, polio, mumps and hepatitis A.

Intradermal vaccine delivery: will new delivery systems transform vaccine administration?

There has been a recent resurgence of interest in intradermal vaccine delivery. The physiological advantages of intradermal vaccine delivery have been known for some time, but the difficulties associated with performing an intradermal injection have historically limited its use. New delivery systems currently in development facilitate convenient intradermal vaccination, unlocking the potential advantages of this delivery route, and potentially transforming vaccine delivery.

Echographic measurement of skin thickness in adults by high frequency ultrasound to assess the appropriate microneedle length for intradermal delivery of vaccines

Skin thickness (epidermis-dermis) across the deltoid, suprascapular, waist and thigh as possible body sites for a new microdelivery system for intradermal (id) inoculation were evaluated using 20 MHz ultrasound echography in 205 women and 137 men aged 18-70 years, in three ethnic groups: Caucasian, Asian and Black. Mean skin thickness was 2.54 mm at the suprascapular, 2.02 mm at the deltoid, 1.91 mm at the waist and 1.55 mm at the thigh. A 1.5 mm microneedle length inserted perpendicularly to the skin surface would ensure the administration of the antigen into the dermal layer, irrespectively of subject gender, age, ethnicity and BMI. The deltoid, suprascapular and waist are the most appropriate body sites.

Vaccines for preventing hepatitis B in health-care workers

BACKGROUND

Hepatitis B virus (HBV) causes acute and chronic liver diseases. Hepatitis B vaccination is recommended for health-care workers.

OBJECTIVES

To assess the beneficial and harmful effects of hepatitis B vaccination in health-care workers.

SEARCH STRATEGY

We searched the trial registers of The Cochrane Hepato-Biliary Group, The Cochrane Library, MEDLINE, and EMBASE to February 2003.

SELECTION CRITERIA

Randomised trials comparing any dose, injection route, injection site, or schedule of hepatitis B plasma-derived vaccines (PDV) or recombinant vaccines (RV) versus placebo, no intervention, or another hepatitis B vaccine in health-care workers.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted the data independently. The reviewers assessed the methodological quality of the trials regarding generation of the allocation sequence, allocation concealment, double blinding, and follow-up. The results were presented as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 21 randomised trials, all with one or more methodological weaknesses. Four trials demonstrated that PDV versus placebo significantly decreased hepatitis B events at maximum follow-up (RR 0.51, 95% CI 0.35 to 0.73). RV did not differ significantly from PDV in eliciting a protective hepatitis B surface antibody (anti-HBs) level in two trials. Both vaccines were well tolerated. Low-dose vaccine (1 or 2 microg) by the intradermal route resulted in significantly more participants without protective anti-HBs level compared with high-dose (10 or 20 microg) by the intramuscular route (RR 1.41, 95% CI 1.13 to 1.76). The intradermal route caused significantly more local adverse events, while the intramuscular route caused significantly more systemic adverse events. The gluteal injection produced significantly more participants without protective anti-HBs level than the deltoid injection. The prevalence of anti-HBs seroconversion by rapid vaccination (0, 1, and 2 months) was significantly lower than that by standard vaccination (0, 1, and 6 months). Booster vaccinations with different RV doses (2.5, 5, 10, 20, or 40 microg) produced similar prevalence of anti-HBs seroconversion in three trials assessing participants who did not respond to previous HBV vaccination.

AUTHORS' CONCLUSIONS

PDV significantly prevents hepatitis B events. RV seems to be able to elicit similar protective anti-HBs levels. The intramuscular route with 20 microg RV was significantly more effective compared with the intradermal route with 2 microg RV as was the standard schedule compared with a rapid schedule and deltoid intramuscular injection compared with the gluteal intramuscular injection. It is unclear if booster vaccination of non-responders offers higher anti-HBs seroconversion and hepatitis B vaccine prevents the infection of hepatitis B mutants in health-care workers.

Low dose intradermal versus high dose intramuscular hepatitis B vaccination in patients on chronic hemodialysis

Patients with end-stage renal disease on hemodialysis (HD) are at high risk for hepatitis B infection. We randomly assigned 86 new patients on HD to receive either 40 microg intramuscular (group 1) or 20 microg intradermal (group 2) recombinant hepatitis B vaccine, in three doses at 0, 1, and 4 months. All patients were seronegative at baseline for hepatitis B surface antigen (HBs-Ag), hepatitis B surface antibody (HBs-Ab), and hepatitis B core antibody (HBc-Ab). HBs-Ab seroconversion rate and antibody titer (ELISA assay) were compared in 27 patients of group 1 and 35 patients of group 2 at 1 month, and in 20 patients of group 1 and 26 patients of group 2 at 6 months after the last vaccine dose. The seroconversion rates (HBs-Ab titer >10 IU/L) were 55.6% and 50% in group 1, and 54.3% and 50% in group 2, at 1 and 6 months, respectively (p = NS). Patients' age, body mass index, serum albumin concentration, and sex distribution were similar in the responders and nonresponders. Intradermal hepatitis B vaccination used at half dose may be a cost saving alternative to intramuscular vaccination in patients on HD. However, the low overall seroconversion rate mandates seeking alternative ways of vaccination in this patient population.

Epidermal powder immunization against influenza

Epidermal powder immunization (EPI) can efficiently deliver powdered protein vaccines to the epidermis. A phase I clinical trial was conducted to evaluate powdered trivalent influenza vaccine delivered using the PowderJect ND5.2 delivery system. Subjects received either Fluvirin IM injection (15 microg of each influenza strain), a single EPI vaccination (15 microg of each influenza strain) or two adjacent EPI (total of 30 microg of each influenza strain). Systemic reactogenicity was similar between control and EPI vaccines. Site reactions following EPI were primarily mild and self-limiting. Seroconversions, titer increases and geometric mean titers to all strains were equivalent or higher in EPI-immunized groups than in controls. Powdered influenza vaccine delivered by EPI is safe and elicits humoral immune responses in humans.

Serum antibody responses after intradermal vaccination against influenza

BACKGROUND

If found to be safe and immunogenic, reduced doses of influenza vaccine given by the intradermal route could increase the number of available doses of vaccine.

METHODS

In an open-label study, we randomly assigned 119 subjects to receive an intradermal injection of trivalent inactivated influenza vaccine, containing 6 mug of hemagglutinin for each antigen (40 percent of the usual dose), and 119 to receive an intramuscular injection of the standard dose of 15 mug of hemagglutinin for each antigen. The two groups were subdivided according to age (18 to 60 years and older than 60 years).

RESULTS

Among subjects who were 18 to 60 years of age, serum antibody responses were vigorous and did not differ significantly between the intradermal and intramuscular groups, and all subjects had hemagglutination-inhibition (HAI) titers of at least 1:40. Although the subjects who were older than 60 years of age also had a vigorous antibody response, there was a trend toward a better response in the intramuscular route, but this finding was significant only for antigen to the H3N2 strain. Nevertheless, 100 percent of older subjects in the intramuscular group and 93 percent of such subjects in the intradermal group had an HAI antibody titer to the H3N2 strain of more than 1:40, and 100 percent in each group had a titer of this level for both the H1N1 and B strains. Local pain was significantly more common in the intramuscular group than in the intradermal group among subjects who were 18 to 60 years of age but not among subjects who were over 60 years old. Signs of local inflammation were significantly more common among subjects in the intradermal group than among those in the intramuscular group, in both age groups.

CONCLUSIONS

As compared with an intramuscular injection of full-dose influenza vaccine, an intradermal injection of a reduced dose resulted in similarly vigorous antibody responses among persons 18 to 60 years of age but not among those over the age of 60 years.

Needle-free topical electroporation improves gene expression from plasmids administered in porcine skin

Electroporation has been shown to increase the potency of DNA vaccines that have demonstrated significant potential in mice. However, there is a need to develop noninvasive or minimally invasive vaccination methods. In pigs, in vivo gene expression was assessed to compare intradermal needle injection to a needle-free dermal BioJect as a means of delivery of plasmids. Each administration method was further tested with and without surface electroporation. Experiments with plasmid DNA encoding luciferase demonstrated that needle-free administration results in higher gene expression levels than needle injection. Electroporation enhanced gene expression for both intradermal delivery methods. Needle-free plasmid injection in combination with electroporation led to a more rapid induction of immune responses compared to other methods of plasmid administration. It was concluded that needle-free topical electroporation significantly enhances gene expression, possibly by improving cellular uptake of plasmid DNA.

Intradermal vaccination of adults with three low doses (2 µg) of recombinant hepatitis B vaccine. I. Seroconversion rate and adverse effects

A total of 250 dentists (53.6% men and 46.4% women), with a mean age of 35.1 +/- 9.8 years, were submitted to serological tests for the diagnosis of hepatitis B (HB)--HBsAg, anti-HBs, anti-HBc, HBeAg, and anti-HBe--using a radioimmunoassay. One or more of these markers were detected in 78 individuals (31.2%) who were excluded from the group to be vaccinated. Of the 172 HB-susceptible individuals, 135 (78.5%) responded to the call and were intradermally injected with three 2 micrograms doses of the Belgian HB recombinant vaccine, applied at an interval of one month between the 1st and 2nd dose and of five months between the 2nd and 3rd dose. A new determination of HB markers carried out 50 days after the 3rd dose showed that 110 (81.5%) individuals had become anti-HBs positive (65.5% good responders and 34.5% poor responders). Mean serum anti-HBs titer of these 110 dentists was 42.4 U S/N, similar in both sexes. The adverse effects analyzed in 106 dentists were: (a) local: pain (12.3%), burning sensation (14.1%), pruritus (25.5%), erythema (28.3%), local heat (18.9%), and a hypochromic spot (32.1%); (b) systemic (4.7%): discomfort in two patients, and fever, anorexia, and asthenia in one patient each. Intradermal administration of a fourth 2 micrograms vaccine dose to 39 dentists (poor or non-responders) increased the total number of anti-HBs-positive individuals from 110 (81.5%) to 114 (84.4%), with the number of good responders increasing from 72 (65.5%) to 85 (74.6%). We conclude that the Belgian recombinant vaccine applied in the scheme used here induces a high rate of seroconversion and causes only mild and transitory adverse effects.

Recombinant hepatitis B vaccine (Engerix-B): a review of its immunogenicity and protective efficacy against hepatitis B

Engerix-B (Hep-B[Eng]) is a noninfectious recombinant DNA vaccine containing hepatitis B surface antigen (HBsAg). It is produced from genetically engineered yeast (Saccharomyces cerevisiae). Intramuscular Hep-B(Eng) [0-, 1-, 6-month schedule] has excellent immunogenicity in healthy neonates and infants, children, adolescents and adults, with seroprotection rates of 85-100% seen approximate, equals 1 month after the final dose of vaccine; seroprotection was defined as an antibody against HBsAg (anti-HBs) titre of > or =10 IU/L. The use of alternative Hep-B(Eng) immunisation schedules (e.g. a 0-, 1-, 2-, 12-month schedule in neonates and infants, 0-, 12-, 24-month or two-dose schedules in children and adolescents, and accelerated schedules in adults) have also been associated with high rates of seroprotection. Seroprotection rates were generally similar with Hep-B(Eng) and the recombinant vaccine Recombivax HB (Hep-B[Rax]) or plasma-derived vaccines (PDVs) approximate, equals 1 month after the final dose (although anti-HBs geometric mean titres were significantly higher with Hep-B[Eng] than with Hep-B[Rax]). One month after the final dose, adults had significantly higher seroprotection rates with the recombinant triple-antigen vaccine Bio-Hep-B (Hep-B[Bio]) than with Hep-B(Eng), although seroprotection rates in healthy infants were similar with Hep-B(Eng) and Hep-B(Bio). Hep-B(Eng) had excellent immunogenicity in several groups considered at high risk of acquiring hepatitis B (e.g. neonates born to hepatitis B carrier mothers and healthcare workers). The immunogenicity of Hep-B(Eng) was reduced in patients with conditions associated with impaired immune function (e.g. patients undergoing haemodialysis or being treated for malignancy), although it had good immunogenicity in patients with diabetes mellitus.Hep-B(Eng) had excellent protective efficacy against HBsAg carriage in healthy infants and children, and in neonates born to hepatitis B carrier mothers (protective efficacy of 95-99%). Hep-B(Eng) also demonstrated good protective efficacy in a number of other high-risk groups. Hep-B(Eng) is generally well tolerated with a tolerability profile similar to that of Hep-B(Rax), Hep-B(Bio) and PDVs. In conclusion, Hep-B(Eng) is a well established, highly immunogenic hepatitis B vaccine with good tolerability and excellent protective efficacy; it offers flexibility through a variety of immunisation schedules. In addition, it appears that Hep-B(Eng) confers immunity for at least 10 years. Hep-B(Eng) has an important role in mass vaccination campaigns against hepatitis B, as well as in groups considered at high risk of acquiring hepatitis B.

Intramuscular versus intradermal administration of anti-hepatitis B vaccine in non-cirrhotic hepatitis C patients

Intradermal vaccination has been proposed as an alternative for the administration of anti-hepatitis B vaccine. Patients (n=66) with chronic viral hepatitis C without cirrhosis were randomised into two groups (intramuscular, n=38; and intradermal, n=28) for prospective immunisation with 20 microg recombinant vaccine, using an ultra-rapid schedule (doses at 0, 15 and 30 days). Sero-conversion (antibody level >/=10 mU/ml) in the intramuscular group was reached by 20, 40 and 72% of patients at days 15, 30 and 60 compared to 4, 8 and 36% for the intradermal group (P=0.010 at day 60). Additionally, levels rose more rapidly in the intramuscular group (P=0.004). Our results do not support the use of intradermal route of immunisation against HBV in HCV patients.

Immunogenicity of hepatitis B vaccines: implications of immune memory

The subunit recombinant hepatitis B virus (HBV) vaccines available in the US differ in hepatitis B surface antigen content. Clinical studies have linked higher antigen formulations with enhanced peak protective antibody levels. This is important for the elderly, smokers, the obese, and the immunocompromised. Immune memory, which is responsible for prolonged protection when HBV vaccine-induced antibody levels become undetectable, may be related to antigen persistence on immunologically active cells. Antigen persistence may be related to antigen content of the vaccine and thereby influences the duration of immunity. Proof of this concept will require additional studies of immune memory in HBV.

Immunogenicity of intradermal hepatitis B vaccination in renal transplant recipients

We investigated intradermal hepatitis B (HBV) vaccination in 24 renal transplant recipients who failed to develop hepatitis B surface antibody (anti-HBs) with intramuscular (i.m.) vaccination. All patients received recombinant HBV vaccine 5 microg intradermally every 2 weeks for 8 doses. Nine patients developed protective levels of anti-HBs (> 10 miu/mL) and two patients developed low levels of anti-HBs (4-6 miu/mL), giving an overall initial response rate of 45.8%. A booster of 40 microg was administered intramuscularly after 1 year. All initial responders developed an anti-HBs response (322.6 +/- 92.0 miu/mL). In addition, four patients who did not respond initially to the intradermal vaccination seroconverted after the booster. Responders (62.5%) and nonresponders had comparable age, gender, immunosuppressive medications, and duration of transplant. In conclusion, renal transplant patients who fail to respond to intramuscular HBV vaccination may benefit from intradermal vaccination followed by an intramuscular booster.

Macroflux microprojection array patch technology: a new and efficient approach for intracutaneous immunization

PURPOSE

We evaluated the Macroflux microprojection array patch technology as a novel system for intracutaneous delivery of protein antigens.

METHODS

Macroflux microprojection array systems (330-microm micro-projection length, 190 microprojections/cm2, 1- and 2-cm2 area) were coated with a model protein antigen, ovalbumin (OVA), to produce a dry-film coating. After system application, microprojection penetration depth, OVA delivery, and comparative immune responses were evaluated in a hairless guinea pig model.

RESULTS

Macroflux microprojections penetrated into hairless guinea pig skin at an average depth of 100 microm with no projections deeper than 300 microm. Doses of I to 80 microg of OVA were delivered via 1- or 2-cm2 systems by varying the coating solution concentration and wearing time. Delivery rates were as high as 20 microg in 5 s. In a prime and boost dose immune response study, OVA-coated Macroflux was most comparable to equivalent doses injected intradermally. Higher antibody titers were observed when OVA was administered with the microprojection array or intradermally at low doses (1 and 5 microg). Macroflux administration at 1- and 5-microg doses gave immune responses up to 50-fold greater than that observed after the same subcutaneous or intramuscular dose. Dry coating an adjuvant, glucosaminyl muramyl dipeptide, with OVA on the Macroflux resulted in augmented antibody responses.

CONCLUSIONS

Macroflux skin patch technology provides rapid and reproducible intracutaneous administration of dry-coated antigen. The depth of skin penetration targets skin immune cells; the quantity of antigen delivered can be controlled by formulation, patch wearing time, and system size. This novel needle-free patch technology may ultimately have broad applications for a wide variety of therapeutic vaccines to improve efficacy and convenience of use.

Low-dose intradermal administration of recombinant hepatitis B vaccine in children: 5-year follow-up study

Several studies have documented the efficacy of low-dose intradermal administration of hepatitis B vaccine. However, little is known about the duration of protection provided by low-dose intradermal administration of hepatitis B vaccine. This study reports results from a 5-year follow up period of 200 healthy children (100 infants and 100 preschool children) immunized intradermally with 2 microg doses of recombinant hepatitis B vaccine (GenHevac B) at months 0,1, and 6. In the 8th week after the third vaccine dose, 97% of the children developed anti-HBs antibodies higher than or equal to 10 mlU ml(-1), and the antiHBs geometric mean titre (GMT) was 676 mlU ml(-1). In month 18 and year 5, the anti-HBs GMT decreased to approximately one-third (220 mlU ml(-1)) and one-tenth (68 mlU ml(-1)) of the initial levels, respectively. However, 87% of the children had protective levels of anti-HBs (> or =10 mlU ml(-1)) after 5 years. Among 156 children followed for 5 years, none became positive for anti-HBc and/or HbsAg. Seven children who were seronegative after 5 years developed anti-HBs antibodies higher than 1000 mlU ml(-1) after an additional 10 microg intramuscular hepatitis B vaccine. Persistent immunologic memory over periods of 5 years or more is evident, the anamnestic antibody response to a booster dose of vaccine, even in these children who have lost antibody. We conclude that intradermal administration of 2 microg recombinant hepatitis B vaccine provides long-term protection against hepatitis B virus in infants and preschool children.

Immunogenicity of two accelerated hepatitis B vaccination protocols in liver transplant candidates

OBJECTIVE

It is common practice to immunize patients against hepatitis B virus infection prior to orthotopic liver transplantation (OLT). We compared the seroprotection rates of two accelerated schedules with a recombinant hepatitis B vaccine in patients awaiting OLT.

DESIGN AND METHODS

Patients were prospectively recruited and vaccinated with either 20 micrograms (group 1, n = 14) or 40 micrograms (group 2, n = 20) hepatitis B surface antigen per dosage. Thirty-nine healthy volunteers served as a historical control group. Patients in all groups were vaccinated with an accelerated schedule (0, 7 and 21 days). All patients underwent clinical and laboratory examinations (HBs antibodies, CD4/CD8 ratio, transaminases).

RESULTS

The accelerated hepatitis B vaccination schedules were well tolerated. Eight weeks after the third injection, no significant differences in seroprotection rates were observed between group 1 (31%) and group 2 (26%). There was no correlation with respect to seroconversion rates and gender, smoking habits or CD4/CD8 ratio.

CONCLUSION

These data suggest that accelerated vaccination schedules with a recombinant hepatitis B vaccine are safe and well-tolerated, but only achieve poor seroconversion rates in OLT candidates. Increasing the vaccine dose to 40 micrograms hepatitis B surface antigen per injection did not result in a higher response rate. Because of the low risk of acquiring de novo hepatitis B infection after transplantation, it should be questioned whether routine hepatitis B vaccination with standard recombinant vaccines prior to liver transplantation should be recommended any longer.

Vaccination against hepatitis B in health care workers

Hepatitis B is the most important infectious occupational disease for health care workers. The high risk of being infected is the consequence of the prevalence of virus carriers in the assisted population, the high frequency of exposure to blood and other body fluids and the high contagiousness of hepatitis B virus (HBV). Vaccination is able to prevent the most threatening consequences of the infection (acute disease and chronic carriage) in responders, even after loss of detectable antibodies. Non-responders to the primary series may benefit from administration of up to three more doses of vaccine (40-70% of initial non-responders show seroconversion to the new series). However, newly developed vaccines that seem more immunogenic are presently under evaluation and should further decrease the number of non-immune workers in the near future. In the mean time, coverage with standard vaccines should be improved also by supplying complete information on the risks of hepatitis B and on the safety and efficacy of active immunisation.