In 2015, The World Health Organization identified the microarray patch (MAP) (also called microneedle patch) platforms as a potential game-changer for vaccine and essential drug distribution and coverage, thereby revolutionizing the way, in which these biomedical products are accessed in low- and middle-income countries (LMICs), where delivery often faces major roadblocks. MAPs are a form of transdermal technology, whereby tens of thousands of microscopic projections attach to the skin through either an applicator or simply by finger pressure. Think of it like a Band-Aid, which, on contact with the skin’s moisture, can initiate a one-time, or long-acting, delivery of a vaccine or medication.
There are currently two types of MAPs in development for vaccine delivery – solid-coated MAPs and dissolving MAPs. Solid-coated MAPs are those which are coated with the liquid formulation and then dried. Dissolvable MAPs are usually formulated from the vaccine itself and dissolve on contact with the skin. For the delivery of drugs, some microarray patches are designed to dissolve upon contact with the skin or vaginal mucosa (when applied with an applicator). While the fullest potential of this delivery platform for vaccines is still being assessed, MAPs have the potential to change the way we deliver, transport, and administer vaccines and therapeutics:
- Most vaccines need to be transported and stored in cold-chain infrastructure that keeps the vaccine between 2 and 8 degrees Celsius, a major roadblock in many regions of the world. MAPs can be formulated to ensure that the vaccine is stable, even in warmer temperatures and where limited cold-chain mechanisms are available. This lowers costs, and may potentially even reduce the amount of antigen needed per dose.
- As easy-to-use and discreet delivery methods, microarray patches hold promise for self-administration, which could expand access to drug treatment and prevention strategies in a range of outpatient settings. Moreover, some patches could be formulated for long-acting, sustained delivery to help reduce by providing needle-free delivery (often a deterrent to receiving vaccinations or medications, especially among pediatric populations).
- Traditional needle and intradermal injections can often require a medically trained operator to administer the dose. As an alternative approach, MAPs can be delivered in non-medical settings, or even self-administered, which expands access to prevention strategies.
Vaccine MAPs are currently in development for human papilloma virus (HPV), influenza, measles and rubella (MR), rabies, inactivated poliovirus vaccine (IPV), tetanus, Bacille Calmette-Guérin, and hepatitis B. Researchers are also working on MAPs for vaccine candidates in early-stage development, such as next-generation rotavirus and dengue vaccines, malaria, hepatitis C, herpes simplex virus 2, West Nile virus, Chikungunya, and HIV-1. In the case of drug delivery, MAPs are being researched for the delivery of long-acting antiretrovirals (ARVs) for the prevention and treatment of HIV infection, insulin, anti-inflammatories, and antivenom, among others. In India, PATH has developed a target product profile (TPP) for anti-rabies vaccine delivery MAPs, and has also started work on a multi-country usability and feasibility study of measles rubella MAPs.
Accelerating the introduction of vaccine and drug delivery through MAPs is a complex process, which involves collaboration among governments, international development organizations, manufacturers, and community stakeholders. This is because the potential health impact (including disease burden and outbreak potential), regulatory and technical success, and potential commercial viability need to be assessed. PATH’s Center for Excellence for MAPs outline four broad priority areas toward the same:
- Defining regulatory pathways for MAP technology;
- Exploring scalable manufacturing opportunities;
- Assessing human factors engineering and usability analysis; and
- Assessing user and health program needs to guide program development.
The disruptive nature of MAP technology as a combination (pharmaceutical and therapeutic) product means it has the potential to usurp traditional methods of immunization and drug delivery. This could be a challenge to scaling up this technology and driving investment. Therefore, to ensure life-saving vaccines and therapeutics, are reaching those most in need, we need to define the potential value of MAPs by generating evidence around usage, handling, and community acceptability. This includes communicating its acceptance among stakeholders, such as healthcare workers. Endorsement by community leaders may also encourage the use of this new technology.
With India’s successes in indigenous vaccine and drug development, and its G20 presidency underway, this is a good time to facilitate sharing of lessons learned among different stakeholders from previous public health programs and push for more innovative investment strategies that center around equity and access for all.