Microneedle technology for immunisation: Perception, acceptability and suitability for paediatric use

Estimating the future global dose demand for measles-rubella microarray patches

Background

Progress toward measles and rubella (MR) elimination has stagnated as countries are unable to reach the required 95% vaccine coverage. Microarray patches (MAPs) are anticipated to offer significant programmatic advantages to needle and syringe (N/S) presentation and increase MR vaccination coverage. A demand forecast analysis of the programmatic doses required (PDR) could accelerate MR-MAP development by informing the size and return of the investment required to manufacture MAPs.

Methods

Unconstrained global MR-MAP demand for 2030-2040 was estimated for three scenarios, for groups of countries with similar characteristics (archetypes), and four types of uses of MR-MAPs (use cases). The base scenario 1 assumed that MR-MAPs would replace a share of MR doses delivered by N/S, and that MAPs can reach a proportion of previously unimmunised populations. Scenario 2 assumed that MR-MAPs would be piloted in selected countries in each region of the World Health Organization (WHO); and scenario 3 explored introduction of MR-MAPs earlier in countries with the lowest measles vaccine coverage and highest MR disease burden. We conducted sensitivity analyses to measure the impact of data uncertainty.

Results

For the base scenario (1), the estimated global PDR for MR-MAPs was forecasted at 30 million doses in 2030 and increased to 220 million doses by 2040. Compared to scenario 1, scenario 2 resulted in an overall decrease in PDR of 18%, and scenario 3 resulted in a 21% increase in PDR between 2030 and 2040. Sensitivity analyses revealed that assumptions around the anticipated reach or coverage of MR-MAPs, particularly in the hard-to-reach and MOV populations, and the market penetration of MR-MAPs significantly impacted the estimated PDR.

Conclusions

Significant demand is expected for MR-MAPs between 2030 and 2040, however, efforts are required to address remaining data quality, uncertainties and gaps that underpin the assumptions in this analysis.

Microneedle-Mediated Transdermal Delivery of Biopharmaceuticals

Transdermal delivery provides numerous benefits over conventional routes of administration. However, this strategy is generally limited to a few molecules with specific physicochemical properties (low molecular weight, high potency, and moderate lipophilicity) due to the barrier function of the stratum corneum layer. Researchers have developed several physical enhancement techniques to expand the applications of the transdermal field; among these, microneedle technology has recently emerged as a promising platform to deliver therapeutic agents of any size into and across the skin. Typically, hydrophilic biomolecules cannot penetrate the skin by passive diffusion. Microneedle insertion disrupts skin integrity and compromises its protective function, thus creating pathways (microchannels) for enhanced permeation of macromolecules. Microneedles not only improve stability but also enhance skin delivery of various biomolecules. Academic institutions and industrial companies have invested substantial resources in the development of microneedle systems for biopharmaceutical delivery. This review article summarizes the most recent research to provide a comprehensive discussion about microneedle-mediated delivery of macromolecules, covering various topics from the introduction of the skin, transdermal delivery, microneedles, and biopharmaceuticals (current status, conventional administration, and stability issues), to different microneedle types, clinical trials, safety and acceptability of microneedles, manufacturing and regulatory issues, and the future of microneedle technology.

Organisational and Structural Drivers of Childhood Immunisation in the European Region: A Systematic Review

Despite the implementation of widespread vaccination programs, the European Health Systems continue to experience care challenges attributable to organizational and structural issues. This study aimed to review the available data on aspects within the organizational and structural domains that might impact vaccination coverage. We searched a comprehensive range of databases from 1 January 2007 to 6 July 2021 for studies that reported quantitative or qualitative research on interventions to raise childhood vaccine coverage. Outcome assessments comprised organizational and structural factors that contribute to vaccine concern among pediatric parents, as well as data reported influencing the willingness to vaccinate. To analyze the risk of bias, the Ottawa, JBI’s (Joanna Briggs Institute) critical appraisal tool, and Amstar quality assessment were used accordingly. The inclusion criteria were met by 205 studies across 21 articles. The majority of the studies were conducted in the United Kingdom (6), the European Union (3), and Italy (3). A range of interventions studied in primary healthcare settings has been revealed to improve vaccination coverage rates including parental engagement and personalization, mandatory vaccination policies, program redesign, supply chain design, administering multiple/combination vaccines, improved vaccination timing and intervals, parental education and reminders, surveillance tools and Supplemental Immunisation Activity (SIA), and information model.

Composite dissolvable microneedle patch for therapy of oral mucosal diseases

A composite microneedle patch (MN patch) is developed for oral transmucosal administration. To improve the oral transmucosal drug delivery efficiency, the composite MN patch is designed to consist of an array of 100 dissolvable microneedles (MNs) with drug-loaded tips and a backing layer. The MNs are composed of two parts, the hyaluronic acid (HA) tip part and the polyvinylpyrrolidone (PVP) base part. Due to the small size and sufficient mechanical strength, the HA-PVP MNs can painlessly penetrate the oral mucosa barrier and deliver drugs directly to the basal layer or submucosa. Betamethasone sodium phosphate (BSP), as the model drug, is concentrated in the HA tip parts to avoid the drug waste caused by mucosa elasticity. Considering the special moist environment and saliva flow in the mouth, a double-layer backing layer composed of a poly(vinyl alcohol) (PVA) adhesive layer and an ethyl cellulose (EC) waterproof layer is designed and constructed, which could reduce the saliva flow effects. The in vitro and in vivo results demonstrate that the MN patch could achieve rapid and efficient BSP release in oral mucosa due to the rapid dissolution of HA. The proposed MN patch provides a novel strategy for the therapy of oral mucosal diseases.

Recent Progress in Microneedles-Mediated Diagnosis, Therapy, and Theranostic Systems

Theranostic system combined diagnostic and therapeutic modalities is critical for the real-time monitoring of disease-related biomarkers and personalized therapy. Microneedles, as a multifunctional platform, are promising for transdermal diagnostics and drug delivery. They have shown attractive properties including painless skin penetration, easy self-administration, prominent therapeutic effects, and good biosafety. Herein, an overview of the microneedles-based diagnosis, therapies, and theranostic systems is given. Four microneedles-based detection methods are concluded based on the sensing mechanism: i) electrochemistry, ii) fluorometric, iii) colorimetric, and iv) Raman methods. Additionally, robust microneedles are suitable for implantable drug delivery. Microneedles-assisted transdermal drug delivery can be primarily classified as passive, active, and responsive drug release, based on the release mechanisms. Microneedles-assisted oral and implantable drug delivery mechanisms are also presented in this review. Furthermore, the key frontier developments in microneedles-mediated theranostic systems as the major selling points are emphasized in this review. These systems are classified into open-loop and closed-loop theranostic systems based on the indirectness and directness of feedback between the transdermal diagnosis and therapy, respectively. Finally, conclusions and future perspectives for next-generation microneedles-mediated theranostic systems are also discussed. Taken together, microneedle-based systems are promising as the new avenue for diagnosis, therapy, and disease-specific closed-loop theranostic applications.

Non-dermal applications of microneedle drug delivery systems

Microneedles (MNs) are micron-scaled needles measuring 100 to 1000 μm that were initially explored for delivery of therapeutic agents across the skin. Considering the success in transcutaneous drug delivery, the application of microneedles has been extended to different tissues and organs. The review captures the application of microneedles to the oral mucosa, the eye, vagina, gastric mucosa, nail, scalp, and vascular tissues for delivery of vaccines, biologics, drugs, and diagnostic agents. The technology has created easy access to the poorly accessible segments of eye to facilitate delivery of monoclonal antibodies and therapeutic agents in management of neovascular disease. Microporation has been reported to drastically improve the drug delivery through the poorly permeable nail plate. Curved microneedles and spatially designed microneedle cuffs have been found to be capable of delivering stem cells and therapeutic macromolecules directly to the cardiac tissue and the vascular smooth muscle cells, respectively. Besides being minimally invasive and patient compliant, the technology has the potential to offer viable solutions to deliver drugs through impermeable barriers owing to the ability to penetrate several biological barriers. The technology has been successful to overcome the delivery hurdles and enable direct delivery of drug to the target sites, thus maximizing the efficacy thereby reducing the required dose. This review is an attempt to capture the non-dermatological applications of microneedles being explored and provides an insight on the future trends in the field of microneedle technology. Pictorial representation of different microneedle application.

Microneedle-Mediated Vaccination: Innovation and Translation

Vaccine administration by subcutaneous or intramuscular injection is the most commonly prescribed route for inoculation, however, it is often associated with some deficiencies such as low compliance, high professionalism, and risk of infection. Therefore, the application of microneedles for vaccine delivery has gained widespread interests in the past few years due to its high compliance, minimal invasiveness, and convenience. This review focuses on recent advances in the development and application of microneedles for vaccination based on different delivery strategies, and introduces the current status of microneedle-mediated vaccination in clinical translation. The prospects for its application including opportunities and challenges are further discussed.

Micro array patch (MAP) for the delivery of thermostable vaccines in Australia: A cost/benefit analysis

BACKGROUND

It is anticipated that transforming the vaccine supply chain from syringe-and-needle to thermostable vaccines enabled by Micro Array Patch (MAP) will result in reduced supply chain costs as well as reduced wastes (environmental impact) and improved safety. This paper provides a thorough cost comparison of the conventional syringe-and-needle vaccine supply chain versus the MAP vaccine supply chain for influenza vaccine delivery in Australia.

OBJECTIVE

To determine the potential cost implications and general benefits of replacing syringe-and-needle flu vaccine with MAP-enabled thermostable flu vaccine in Australia.

METHODS

We first provide a snapshot of the existing flu vaccine supply chain in Australia including its limitations and opportunities for improvement. Data/information is collected through interviewing the key stakeholders across vaccine supply chain including vaccine manufacturers, logistics providers, clinics, hospitals, and pharmacies. A cost/benefit analysis of the anticipated supply chain of the MAP-enabled vaccine will reveal the opportunities and challenges of supply chain transformation for flu vaccine delivery in Australia.

FINDINGS

Our high-level practice-informed cost/benefit analysis identifies cold chain removal as an important source of cost saving, but administrative cost savings appear to be even more significant (e.g., time saving for nurses and those involved in cold chain management). Our analysis also identifies the key benefits and limitations of vaccine supply chain transformation in Australia.

CONCLUSION

We conclude that the benefits of moving from syringe-and-needle vaccines to thermostable MAP-delivered vaccines are beyond transportation and storage cost saving. Potential benefits through cost saving, waste reduction, and service level improvement are discussed along with various safety and wellbeing consequences as well as directions for future research in this area.

Transforming the vaccine supply chain in Australia: Opportunities and challenges

BACKGROUND

Analyzing potential benefits of thermostable vaccines delivered through Micro Array Patch (MAP) has received great attention in low and middle-income countries. The experience may or may not be the same in developed countries where the infrastructure is more developed. It is anticipated that transforming the vaccine supply chain from syringe-and-needle to thermostable MAP-delivered vaccines will result in reduced supply chain costs - including manufacturing/supply, logistics/distribution, and administration costs - as well as reduced wastes and improved safety. This paper provides an end-to-end supply chain analysis comparing the key aspects (cost, safety and environmental aspects) of the conventional syringe-and-needle vaccine supply chain with those of the MAP vaccine supply chain for influenza vaccine delivery in Australia. Directions for future research in this area will be provided.

OBJECTIVE

To determine the potential supply chain impacts of replacing syringe-and-needle flu vaccine with MAP-enabled thermostable flu vaccine in Australia.

METHODS

We analyze the current flu vaccine supply chain in Australia to identify practical limitations and opportunities for improvement. Data/information is collected through interviewing the key stakeholders across vaccine supply chain including vaccine manufacturers, logistics providers, clinics, hospitals, and pharmacies.

FINDINGS

A detailed practice-informed analysis is completed on the key operations of the flu vaccine supply chain. Barriers and limitations of the conventional flu vaccine are discussed, along with potential improvements that can be achieved through the implementation of MAP-enabled flu vaccine delivery. We discuss how technology-driven innovations can help advance vaccine supply chains, improve vaccine visibility, reduce wastes, and enable informed decision-making.

CONCLUSION

We find that the benefits of moving from syringe-and-needle vaccines to thermostable MAP-delivered vaccines are beyond transportation and storage cost saving. Potential benefits through cost saving, waste reduction, and service level improvement are discussed along with various safety and wellbeing consequences followed by directions for future research in this area.

Transdermal approaches to vaccinations in the COVID-19 pandemic era

The COVID-19 pandemic has necessitated rapid vaccine development for the control of the disease. Most vaccinations, including those currently approved for COVID-19 are administered intramuscularly and subcutaneously using hypodermic needles. However, there are several disadvantages including pain and fear of needlesticks, the need for two doses, the need for trained health care professionals for vaccine administration, and barriers to global distribution given the need for cold supply chain. Recently, transdermal techniques have been under investigation for vaccines including COVID-19. Microneedle array technology utilizes multiple microscopic projections from a plate which delivers a vaccine in the form of a patch placed on the skin, allowing for painless antigen delivery with improved immune response. In this review, we discuss challenges of existing vaccines and review the literature on the science behind transdermal vaccines including microneedles, current evidence of application in infectious diseases including COVID-19, and considerations for implementation and global access.

Microneedles in Smart Drug Delivery

Significance: In biomedical setup, at large, and drug delivery, in particular, transdermal patches, hypodermal needles, and/or dermatological creams with the topical appliance are among the most widely practiced routes for transdermal drug delivery. Owing to the stratum corneum layer of the skin, traditional drug delivery methods are inefficient, and the effect of the administered therapeutic cues is limited. Recent Advances: The current advancement at the microlevel and nanolevel has revolutionized the drug delivery sector. Particularly, various types of microneedles (MNs) are becoming popular for drug delivery applications because of safety, patient compliance, and smart action. Critical Issues: Herein, we reviewed state-of-the-art MNs as a smart and sophisticated drug delivery approach. Following a brief introduction, the drug delivery mechanism of MNs is discussed. Different types of MNs, that is, solid, hollow, coated, dissolving, and hydrogel forming, are discussed with suitable examples. The latter half of the work is focused on the applied perspective and clinical translation of MNs. Furthermore, a detailed overview of clinical applications and future perspectives is also included in this review. Future Directions: Regardless of ongoing technological and clinical advancement, the focus should be diverted to enhance the efficacy and strength of MNs. Besides, the possible immune response or interference should also be avoided for successful clinical translation of MNs as an efficient drug delivery system.

Development of vaccine formulations: past, present, and future

The current situation, heavily influenced by the ongoing pandemic, puts vaccines back into the spotlight. However, the conventional and traditional vaccines present disadvantages, particularly related to immunogenicity, stability, and storage of the final product. Often, such products require the maintenance of a “cold chain,” impacting the costs, the availability, and the distribution of vaccines. Here, after a recall of the mode of action of vaccines and the types of vaccines currently available, we analyze the past, present, and future of vaccine formulation. The past focuses on conventional formulations, the present discusses the use of nanoparticles for vaccine delivery and as adjuvants, while the future presents microneedle patches as alternative formulation and administration route. Finally, we compare the advantages and disadvantages of injectable solutions, nanovaccines, and microneedles in terms of efficacy, stability, and patient-friendly design.

Different approaches to vaccine formulation development, the conventional vaccine formulations from the past, the current development of lipid nanoparticles as vaccines, and the near future microneedles formulations are discussed in this review. 

The potential role of using vaccine patches to induce immunity: platform and pathways to innovation and commercialization

Introduction: In the last two decades, the evidence related to using vaccine patches with multiple short projections (≤1 mm) to deliver vaccines through the skin increased significantly and demonstrated their potential as an innovative delivery platform.Areas covered: We review the vaccine patch literature published in English as of 1 March 2019, as well as available information from key stakeholders related to vaccine patches as a platform. We identify key research topics related to basic and translational science on skin physical properties and immunobiology, patch development, and vaccine manufacturing.Expert opinion: Currently, vaccine patch developers continue to address some basic science and other platform issues in the context of developing a potential vaccine patch presentation for an existing or new vaccine. Additional clinical data and manufacturing experience could shift the balance toward incentivizing existing vaccine manufactures to further explore the use of vaccine patches to deliver their products. Incentives for innovation of vaccine patches differ for developed and developing countries, which will necessitate different strategies (e.g. public-private partnerships, push, or pull mechanisms) to support the basic and applied research needed to ensure a strong evidence base and to overcome translational barriers for vaccine patches as a delivery platform.

Technology update: dissolvable microneedle patches for vaccine delivery

Despite vaccination representing one of the greatest advances of modern preventative medicine, there remain significant challenges in vaccine distribution, delivery and compliance. Dissolvable microarray patches or dissolving microneedles (DMN) have been proposed as an innovative vaccine delivery platform that could potentially revolutionize vaccine delivery and circumvent many of the challenges faced with current vaccine strategies. DMN, due to their ease of use, lack of elicitation of pain response, self-disabling nature and ease of transport and distribution, offer an attractive delivery option for vaccines. Additionally, as DMN inherently targets the uppermost skin layers, they facilitate improved vaccine efficacy, due to direct targeting of skin antigen-presenting cells. A plethora of publications have demonstrated the efficacy of DMN vaccination for a range of vaccines, with influenza receiving particular attention. However, before the viable adoption of DMN for vaccination purposes in a clinical setting, a number of fundamental questions must be addressed. Accordingly, this review begins by introducing some of the key barriers faced by current vaccination approaches and how DMN can overcome these challenges. We introduce some of the recent advances in the field of DMN technology, highlighting the potential impact DMN could have, particularly in countries of the developing world. We conclude by reflecting on some of the key questions that remain unanswered and which warrant further investigation before DMNs can be utilized in clinical settings.

Skin delivery of trivalent Sabin inactivated poliovirus vaccine using dissolvable microneedle patches induces neutralizing antibodies

The cessation of the oral poliovirus vaccine (OPV) and the inclusion of inactivated poliovirus (IPV) into all routine immunization programmes, strengthens the need for new IPV options. Several novel delivery technologies are being assessed that permit simple yet efficacious and potentially dose-sparing administration of IPV. Current disadvantages of conventional liquid IPV include the dependence on cold chain and the need for injection, resulting in high costs, production of hazardous sharps waste and requiring sufficiently trained personnel. In the current study, a dissolvable microneedle (DMN) patch for skin administration that incorporates trivalent inactivated Sabin poliovirus vaccine (sIPV) was developed. Microneedles were physically stable in the ambient environment for at least 30 min and efficiently penetrated skin. Polio-specific IgG antibodies that were able to neutralize the virus were induced in rats upon administration using trivalent sIPV-containing microneedle patches. These sIPV-patch-induced neutralizing antibody responses were comparable to higher vaccine doses delivered intramuscularly for type 1 and type 3 poliovirus serotypes. Moreover, applying the patches to the flank elicited a significantly higher antibody response compared to their administration to the ear. This study progresses the development of a skin patch-based technology that would simplify vaccine administration of Sabin IPV and thereby overcome logistic issues currently constraining poliovirus eradication campaigns.

Potential use of microarray patches for vaccine delivery in low- and middle- income countries

Microarray patches (MAPs), also referred to as microneedle patches, are a novel methodology that have the potential to overcome barriers to vaccine delivery in low- and middle-income countries (LMICs), and transform the way that vaccines are delivered within immunization programs. The World Health Organization's Initiative for Vaccine Research and its partners are working to understand how MAPs could ease vaccine delivery and increase equitable access to vaccines in LMICs. Global stakeholders have been engaged to evaluate technical, economic, and programmatic challenges; to validate assumptions where possible; and to propose areas of focus to facilitate future vaccine-MAP product development. This report summarizes those learnings.

End-user acceptability study of the nanopatch™; a microarray patch (MAP) for child immunization in low and middle-income countries

A promising new delivery technology, the microarray patch (MAPs) consists of an array of small solid-coated or dissolvable needles, up to one mm in length, that administers a dry formulation of a vaccine or pharmaceutical. This study is not a real-life evaluation study but determines the anticipated acceptability of the Nanopatch™, a solid microarray patch device, in Benin, Nepal and Vietnam for vaccine delivery, and identifies factors that could improve the acceptability of the technology to increase measles immunization coverage. This study combined several evaluation methods, including simulation of vaccine administration on children and in-depth interviews with key stakeholders, healthcare workers, community health volunteers, caretakers, and community representatives. A total of 314 people participated in the study. The overall rate of total acceptability of the patch for child immunization was 92.7%. General opinions were very positive, providing clinical studies confirm that MAP administration is demonstrated to be painless, safe and effective for infectious disease prevention. The study participants were asked to consider the best strategy to introduce such vaccine delivery innovation. Firstly, delivery by skilled healthcare workers at the healthcare facilities will be preferred to establish the technology. Following this, administration by selected volunteers and outreach delivery may be possible, though under the supervision of skilled healthcare workers. This study's protocol received approval from the World Health Organization (WHO) Ethical Research Committee (ERC0002813) and the national IRB in Benin, Nepal and Vietnam.

Low cost additive manufacturing of microneedle masters

PURPOSE

Microneedle patches are arrays of tiny needles that painlessly pierce the skin to deliver medication into the body. Biocompatible microneedles are usually fabricated via molding of a master structure. Microfabrication techniques used for fabricating these master structures are costly, time intensive, and require extensive expertise to control the structure's geometry of the structure, despite evidence that microneedle geometry is a key design parameter. Here, a commercially available 3D printer is utilized, for the first time, to quickly and easily manufacture microneedle masters.

DESIGN/METHODOLOGY/APPROACH

Because commercially available 3D printers are not typically used for micron-scale fabrication, the influence of three different sources of error- stair-stepping, aliasing, and light abberations- on the resulting structure is investigated. A custom Matlab code is written to control the light intensity projected off of each individual micromirror (through grayscale) at a given time. The effect of the layer height, the number of layers, and grayscale on the sharpness, surface texture, and dimensional fidelity of the final structure is described.

FINDINGS

The Autodesk Ember is successfully utilized to fabricate sharp microneedles with a tip radius of approximately 15 μm in less than 30 min per patch (as compared to weeks to months for existing approaches). Utilization of grayscale improves surface texture and sharpness, and dimensional fidelity within ±5% of desired dimensions is achieved.

ORIGINALITY/VALUE

The described 3D printing technique enables investigators to accurately fabricate microneedles within minutes at low cost. Rapid, iterative optimization of microneedle geometry through 3D printing will accelerate microneedle research through improved understanding of the relationship between microneedle structure and function.

Stable incorporation of GM-CSF into dissolvable microneedle patch improves skin vaccination against influenza

The widely used influenza subunit vaccine would benefit from increased protection rates in vulnerable populations. Skin immunization by microneedle (MN) patch can increase vaccine immunogenicity, as well as increase vaccination coverage due to simplified administration. To further increase immunogenicity, we used granulocyte-macrophage colony stimulating factor (GM-CSF), an immunomodulatory cytokine already approved for skin cancer therapy and cancer support treatment. GM-CSF has been shown to be upregulated in skin following MN insertion. The GM-CSF-adjuvanted vaccine induced robust and long-lived antibody responses cross-reactive to homosubtypic and heterosubtypic influenza viruses. Addition of GM-CSF resulted in increased memory B cell persistence relative to groups given influenza vaccine alone and led to rapid lung viral clearance following lethal infection with homologous virus in the mouse model. Here we demonstrate that successful incorporation of the thermolabile cytokine GM-CSF into MN resulted in improved vaccine-induced protective immunity holding promise as a novel approach to improved influenza vaccination. To our knowledge, this is the first successful incorporation of a cytokine adjuvant into dissolvable MNs, thus advancing and diversifying the rapidly developing field of MN vaccination technology.

Acceptability of microneedle-patch vaccines: A qualitative analysis of the opinions of parents

INTRODUCTION

Vaccines incorporated into microneedle-based patch platforms offer advantages over conventional hypodermic injections. However, the success and clinical utility of these platforms will depend on its acceptance among stakeholders. Minimal focus has been placed on determining parents' acceptability of microneedle-patch vaccines intended for paediatric use. This qualitative study probes the perceived acceptability of microneedle technology for paediatric vaccination in a parent population.

RESEARCH DESIGN AND METHODOLOGY

Focus groups (n=6) were convened through purposive sampling of Cork city primary schools. Discussions were audio-recorded, transcribed verbatim, anonymised, independently verified and analysed by thematic analysis, with constant comparison method applied throughout.

RESULTS

The opinions of 32 parents were included. All participants declared that their children were fully vaccinated. Five core themes were identified and defined as: (i) concern, (ii) suitability for paediatric use, (iii) potential for parental administration, (iv) the role of the healthcare professional and (v) special populations. Drivers for acceptance include; concerns with current vaccines and vaccination programmes; attributes of microneedle-patch (reduced pain, bleeding, fear and increased convenience) and endorsement by a healthcare professional. Barriers to acceptance include; lack of familiarity, concerns regarding feasibility and suitability in paediatrics, allergic potential, inability to confirm delivery and potential reduction in vaccine coverage.

CONCLUSION

This is the first study to explore parental acceptance of microneedle-patch vaccines. Capturing the opinions of parents, the ultimate decision makers in paediatric vaccination, is crucial in the understanding of the eventual uptake of microneedle technology and therefore adds to literature currently available. This study has revealed that even "vaccine-acceptors"; parents who agree with, or do not question vaccination, will question the safety and efficacy of this novel method. Participants in this study remained tentative. However, the study has also revealed that endorsement by healthcare professionals could reduce this tentativeness, thereby identifying the role of healthcare professionals in disseminating information and providing support to parents. An increased awareness of developments in microneedle technology is needed to permit informed decision-making by parents.

Tolerability, usability and acceptability of dissolving microneedle patch administration in human subjects

To support translation of microneedle patches from pre-clinical development into clinical trials, this study examined the effect of microneedle patch application on local skin reactions, reliability of use and acceptability to patients. Placebo patches containing dissolving microneedles were administered to fifteen human participants. Microneedle patches were well tolerated in the skin with no pain or swelling and only mild erythema localized to the site of patch administration that resolved fully within seven days. Microneedle patches could be administered by hand without the need of an applicator and delivery efficiencies were similar for investigator-administration and self-administration. Microneedle patch administration was not considered painful and the large majority of subjects were somewhat or fully confident that they self-administered patches correctly. Microneedle patches were overwhelmingly preferred over conventional needle and syringe injection. Altogether, these results demonstrate that dissolving microneedle patches were well tolerated, easily usable and strongly accepted by human subjects, which will facilitate further clinical translation of this technology.

Ebola Vaccination Using a DNA Vaccine Coated on PLGA-PLL/γPGA Nanoparticles Administered Using a Microneedle Patch

Ebola DNA vaccine is incorporated into PLGA-PLL/γPGA nanoparticles and administered to skin using a microneedle (MN) patch. The nanoparticle delivery system increases vaccine thermostability and immunogenicity compared to free vaccine. Vaccination by MN patch produces stronger immune responses than intramuscular administration.