Inadequate response to intradermal hepatitis A vaccine

Cryogel vaccines effectively induce immune responses independent of proximity to the draining lymph nodes

The delivery location of traditional vaccines can impact immune responses and resulting efficacy. Cryogel-based cancer vaccines, which are typically injected near the inguinal lymph nodes (iLNs), recruit and activate dendritic cells (DC) in situ, induce DC homing to the iLNs, and have generated potent anti-tumor immunity against several murine cancer models. However, whether cryogel vaccination distance to a draining LN affects the kinetics of DC homing and downstream antigen-specific immunity is unknown, given the heightened importance of the scaffold vaccine site. We hypothesized that vaccination near the iLNs would lead to more rapid DC trafficking to the iLNs, thereby inducing faster and stronger immune responses. Here, mice were injected with cryogel vaccines against ovalbumin either adjacent or distal to the iLNs, and the resultant DC trafficking kinetics, T cell phenotypes, antigen-specific T cell and humoral responses, and prophylactic efficacy in an ovalbumin-expressing tumor model were assessed. Cryogel vaccines induced potent, long-lasting antigen-specific immune responses independent of distance to the iLNs, with no significant differences in DC trafficking kinetics, ovalbumin-specific T cell and antibody responses, or prophylactic efficacy. Moreover, DC trafficking and activation state were not impacted when cryogels were injected near a tumor. These results demonstrate a flexibility in vaccination location for scaffold-based vaccines, independent of draining LN distance.

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.

Recent insights into cutaneous immunization: How to vaccinate via the skin

Technologies and strategies for cutaneous vaccination have been evolving significantly during the past decades. Today, there is evidence for increased efficacy of cutaneously delivered vaccines allowing for dose reduction and providing a minimally invasive alternative to traditional vaccination. Considerable progress has been made within the field of well-established cutaneous vaccination strategies: Jet and powder injection technologies, microneedles, microporation technologies, electroporation, sonoporation, and also transdermal and transfollicular vaccine delivery. Due to recent advances, the use of cutaneous vaccination can be expanded from prophylactic vaccination for infectious diseases into therapeutic vaccination for both infectious and non-infectious chronic conditions. This review will provide an insight into immunological processes occurring in the skin and introduce the key innovations of cutaneous vaccination technologies.

Delivery systems for intradermal vaccination

Intradermal (ID) vaccination can offer improved immunity and simpler logistics of delivery, but its use in medicine is limited by the need for simple, reliable methods of ID delivery. ID injection by the Mantoux technique requires special training and may not reliably target skin, but is nonetheless used currently for BCG and rabies vaccination. Scarification using a bifurcated needle was extensively used for smallpox eradication, but provides variable and inefficient delivery into the skin. Recently, ID vaccination has been simplified by introduction of a simple-to-use hollow microneedle that has been approved for ID injection of influenza vaccine in Europe. Various designs of hollow microneedles have been studied preclinically and in humans. Vaccines can also be injected into skin using needle-free devices, such as jet injection, which is receiving renewed clinical attention for ID vaccination. Projectile delivery using powder and gold particles (i.e., gene gun) have also been used clinically for ID vaccination. Building off the scarification approach, a number of preclinical studies have examined solid microneedle patches for use with vaccine coated onto metal microneedles, encapsulated within dissolving microneedles or added topically to skin after microneedle pretreatment, as well as adapting tattoo guns for ID vaccination. Finally, technologies designed to increase skin permeability in combination with a vaccine patch have been studied through the use of skin abrasion, ultrasound, electroporation, chemical enhancers, and thermal ablation. The prospects for bringing ID vaccination into more widespread clinical practice are encouraging, given the large number of technologies for ID delivery under development.

Virosomal hepatitis a vaccine: comparing intradermal and subcutaneous with intramuscular administration

BACKGROUND

Vaccination against hepatitis A virus (HAV) is unaffordable to many developing countries. Substantial reductions in cost occur when vaccines are administered intradermally at low doses. Aluminum-free HAV vaccines are considered more suitable for intradermal use than traditional vaccines which can cause long-lasting local reactions. Thus, we compared the immunogenicity and safety of an aluminum-free virosomal HAV vaccine (Epaxal) administered by different routes: intradermal (i.d.), subcutaneous (s.c.), and intramuscular (i.m.).

METHODS

Two open pilot studies were conducted as sub-studies of a large lot consistency trial. Healthy subjects aged 18 to 45 were enrolled. Study 1 compared two i.d. regimens of a lower dose of Epaxal [0.1 mL (4.8 IU), one or two injection sites] with i.m. administration of the standard dose [0.5 mL (24 IU)]. Study 2 compared the s.c. with the i.m. administration of the standard dose. At month 12, subjects in study 1 received a booster dose of 0.1 mL i.d. or 0.5 mL i.m.; subjects in study 2 received 0.5 mL via the respective route (s.c. or i.m.). Serum was tested for antibodies at baseline, 2 weeks (study 1), and 1 and 6 months after the primary vaccination as well as prior and 1 month after the booster dose. Incidences of solicited and unsolicited adverse events were recorded.

RESULTS

Seroprotection rates (anti-HAV geometric mean concentration of > or =20 mIU/mL) after 1 month ranged from 93.2% to 100% in all groups and remained high until month 12 (range 85.2&-90.2%). Complete (100%) seroprotection was achieved by all subjects in all groups after booster vaccination. All routes of administration were well tolerated. Local reactions were more common in subjects vaccinated i.d. and s.c. than i.m.

CONCLUSIONS

The aluminum-free virosomal HAV vaccine Epaxal is highly immunogenic and well tolerated when administered either via i.d., s.c., or i.m. Vaccination via the i.d. route may confer significant cost savings over the conventional i.m. route.

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.

Aloe polymannose enhances anti-coxsackievirus antibody titres in mice

Aloe polymannose (AP), a high mannose biological response modifier (BRM) purified from the Aloe barbadensis Miller plant, was tested for activity in enhancing antibody titres against coxsackievirus B3 (CVB3) and CVB3-induced myocarditis in murine models of the disease. Inoculation of mice with AP over a range of three nontoxic doses and in varying schedules did not reduce virus titres in heart tissues or ameliorate virus-induced cardiopathological alterations during acute disease. However, this BRM was found to significantly enhance titres of anti-CVB3 antibodies produced during acute infection of three strains of mice with CVB3. Simultaneous intraperitoneal inoculation of AP at a dose of 0.5 mg/kg body weight per mouse with purified CVB3 significantly increased ELISA titres of anti-CVB3 antibodies and the proportion of mice with these titres, compared with similar parameters in mice inoculated only with CVB3. The data conclusively show that AP can immunopotentiate antibody production against capsid protein epitopes of a nonenveloped picornavirus and suggest this BRM (AP) might be of benefit in enhancing antibody titres against other enteroviruses during a natural infection and poliovirus vaccine strains.

Hepatitis A vaccine administration: comparison between jet-injector and needle injection

INTRODUCTION

Type A hepatitis virus (HAV) is a serious health problem throughout the world and can be spread via fecal-oral contact. Both immune globulin and an HAV vaccine provide protection, but the vaccine gives complete protection. Efficacy of methods of vaccination in relation to the formation of anti-HAV antibodies is unclear; thus, this study seeks to determine if significant differences exist between the syringe as compared to the jet injection technique. The purpose of this study was to compare in a randomized trial Biojet jet-injection system to a needle-syringe method. To determine if a significant difference between these two methods in seroconversion rates or geometric mean titers of anti HAV antibody occurs at day 15, 30, and 210 days after vaccination.

METHOD

Anti-HAV IgG(-) adult hospital employees were randomized to receive 1440 EL.U of hepatitis a vaccine (HAVRIX(R)) in 2 doses by either needle or jet-injector (Biojector(R)) system at month 0 and 6. HAV seroconversion titer results were measured by the Boehringer-Mannheim method.

RESULTS/DISCUSSION

A higher proportion of persons who received HAV vaccine via the Biojector(R) seroconverted with anti-HAV level >/=20 mIU at day 15, 30, and month 7 when compared with a needle injection.Side-effect profiles reported by participants in both methods were below those identified in current published and insert information, but the Biojector(R) had greater local reactivity in all categories when compared to the needle method.