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There is an urgent need for new tools and approaches to reach the 20 million infants that are not fully immunized each year.1 The majority of the 1.5 million deaths that result from vaccine preventable diseases occur in just a handful of countries, with the weakest healthcare infrastructure, and where it is an enormous challenge to reach remote or conflict areas. Vaccine delivery in these countries is hampered by the requirement for most vaccines to be refrigerated from the point of production to the point of administration, the need to correctly prepare the vaccine by a trained healthcare worker, and the fact that many caregivers and children don’t like needles or the pain associated with them.2
Most vaccines are manufactured as multi-dose vials to reduce cost, but this presentation means there is reluctance to open the vaccine if there are not multiple children at the facility at the moment of vaccination. Microarray patches (MAPs) are designed to address these issues and revolutionise vaccine delivery in low and middle income countries.
MAPs consist of a cluster of thousands of microneedles less than 1mm long attached to a backing, which can be applied to the skin with finger pressure or an applicator. The microneedles reach the dermis or epidermis to diffuse or dissolve the vaccine to immune cells that evoke a strong immune response. MAPs offer significant advantages over the existing vaccine presentations.3
Can be kept outside the cold chain
They are designed to deliver a single dose without any vaccine preparation and are easy to apply. They can potentially be kept outside the cold chain, facilitating the delivery by minimally trained personnel in hard to reach and remote places.4 As MAPs target the vaccine directly to immune cells, they could allow for a reduction in the vaccine dose as compared to conventional delivery of vaccines, which can reduce both cost and increase the number of available doses during vaccine shortages.5,6
MAPs are in product development for influenza7–9, Hepatitis B10,11 (HepB), Human Papillomavirus12 (HPV), Measles-Rubella13 (MR) and other vaccines. The first dose of HepB vaccine is recommended to be given at birth, and vaccination often takes place outside of a healthcare facility by minimally trained personnel.14 A MAP HepB thermostable vaccine that is easy to transport and deliver could incrementally increase the proportion of vaccinated infants with HepB at birth.10
Combating Hepatitis B and Measles-Rubella
The MR vaccine is a multi-dose vial with stringent temperature requirements that needs to be used within six hours from opening. A MAP-MR vaccine that is thermostable, easy to deliver and single dose would facilitate delivery of vaccines in outbreaks and during immunisation campaigns.13 Delivery of HepB and MR by MAPs are considered as potential game-changers for the elimination agendas of these vaccines.
There is a clear public health imperative to develop the MAPs delivery platform for vaccines. The implementation of this delivery strategy could significantly increase the proportion of vaccinated children in the world’s most impoverished areas and save lives.
Sources:
1. UNICEF. WUENIC Analytics. (2019).
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8. Fernando, G. J. P. et al. Safety, tolerability, acceptability and immunogenicity of an influenza vaccine delivered to human skin by a novel high-density microprojection array patch (NanopatchTM). Vaccine (2018). doi:10.1016/j.vaccine.2018.05.053.
9. Hirobe, S. et al. Clinical study and stability assessment of a novel transcutaneous influenza vaccination using a dissolving microneedle patch. Biomaterials (2015). doi:10.1016/j.biomaterials.2015.04.007.
10. Poirier, D. et al. Hepatitis B surface antigen incorporated in dissolvable microneedle array patch is antigenic and thermostable. Biomaterials (2017). doi:10.1016/j.biomaterials.2017.08.038.
11. Qiu, Y. et al. DNA-based vaccination against hepatitis B virus using dissolving microneedle arrays adjuvanted by cationic liposomes and CpG ODN. Drug Deliv. (2016). doi:10.3109/10717544.2014.992497.
12. Corbett, H. J., Fernando, G. J. P., Chen, X., Frazer, I. H. & Kendall, M. A. F. Skin vaccination against cervical cancer associated human papillomavirus with a novel micro-projection array in a mouse model. PLoS One (2010). doi:10.1371/journal.pone.0013460.
13. Joyce, J. C. et al. A Microneedle Patch for Measles and Rubella Vaccination Is Immunogenic and Protective in Infant Rhesus Macaques. in Journal of Infectious Diseases (2018). doi:10.1093/infdis/jiy139.
14. World Health Organization (WHO). Hepatitis B vaccines: WHO position paper – July 2017. World Heal. Organ. Geneva (2016). doi:10.1186/1750–9378‑2–15.
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Authors: Mateusz Hasso-Agopsowicz, Project Manager, Initiative for Vaccine Research, WHO, Geneva, Switzerland und Birgitte Giersing, Technical Officer, Initiative for Vaccine Research, WHO, Geneva, Switzerland
Photo: shutterstock.com/Cheers Group