nanopatch consists of an around 1cm2 piece of silicon with approximately 20,000 projections on it, each measuring around 60-100 micrometres in length (see figure 1) (Clemons, 2016). The projections are engraved onto the silicon using deep reactive ion etching, where well-controlled ions in an electromagnetic field are used to scratch away at the silicon and leave evenly sized and spaced projections (Clemons, 2016). The projections are coated with a dry form of the required vaccine (Fernando et al., 2010). The vaccine being dry means it does not require special storage facilities and can be kept at 23°c for up to a year without it becoming less effective (Kendall, 2013).
The patch is applied to the skin with either an applicator (see figure 2) or by pressing it into the skin (Kendall, 2013). When applied the projections break through the dead skin cells of the stratum corneum, the outer most layer of skin, to the living epidermis and dermis (see figure 3) without causing discomfort to the person by stimulating pain receptors (Pearson et al. 2013). Within two minutes the vaccine is released into the skin due to its moisture (Vaxxas, 2017).
By contrast, a needle injects the vaccine into a person’s muscle tissue and an immune response occurs almost identical to the response with the Nano patch (see figure X). However, the concentration of antigen presenting cells in the muscle tissue is far less than in the epidermis and dermis (Kendall, 2012).
Vaccines work by having a non-harmful version of the virus/bacteria being vaccinated against enter the body. The vaccine can either contain: a live attenuated virus, which is a weakened form of the whole virus; an inactivated virus, which is a dead form of the whole virus, virus like particles, which are viral protein that don’t contain any genetic material; a subunit of a virus or bacteria, which consists of just its antigens, the part of the virus or bacteria which stimulates the body immune response (Suh et al., 2013)
When the vaccines enter the epidermis and dermis of the skin it comes into contact with Langerhans cells (Kendall, 2012). The Langerhans cells are antigen presenting cells meaning they engulf the virus or bacteria through endocytosis, break it down then move the virus’/bacteria’s antigens to its surface (Khan, 2010). The Langerhans cells then move the lymph node where T cells, which each have unique receptors on them, scan the cells until one can attach to the antigens on a Langerhans cell (Kurzgesagt, 2014). Once a T cells receptor matches to a Langerhans cells it makes copies of itself as well as memory T cells. Some of the T cells go further into the immune system to activate B cells which make antibodies to disable and neutralise the invading virus or bacteria (Kurzgesagt, 2014). Once the immune system has rid the body of the vaccine the memory T and B cells continue to live in the body in case the real version of the virus or bacteria returns so the body is able to recognise, produce the antibodies for and kill it before it can harm the body (Kurzgesagt, 2014).
It is estimated 1.5 million children die every year from diseases that could have been prevented by vaccines but were not because they were unable to access safe and effective vaccines to social, environmental and economic barriers (BBC, 2013). Replacing the needle and syringe with the nanopatch could lessen these barriers as well as provide solutions to other vaccine related problems.
The muscle, where needles deliver vaccines contain significantly fewer cells involved with the
immune system than the epidermis and dermis, meaning less vaccine is required on the nanaopatch
than in a syringe for the same effect. A study found that Five times less vaccine was needed to
produce the same immunity to a form of the influenza virus in mice using a nanopatch than was
needed using a needle (Suh et al., 2013). Another source stated that only one-thirtieth of a regular dose
of an influenza vaccine would be requiring on a nanopatch for the same result provided by a needle
(Chen et al., 2011). The decreased amount of vaccine needed combined with the fact that nanopatches
only need a very small amount of silicon as opposed to a syringe and vial would decrease the overall
cost of a vaccine. Currently, a vaccine costs around $50, however, it is estimated that with the
nanopacth the cost could be decreased to $1 greatly increasing the number of people who could afford
vaccines in developed a nd developing countries (Kendall, 2013).
One of the biggest economic and environmental barriers currently associated with liquid vaccines is that they require refrigeration to remain between 2-8°c or else the vaccine will become less effective (Western Australia Department of health, undated). This makes transporting vaccines to or storing vaccines in rural areas difficult and costly as refrigeration or insulation is expensive, heavy and needs a constant supply of electricity to maintain, which is often unavailable (see figure 4). As the vaccine on a nanopatch is dry it does not require refrigeration and as previously mentioned can be stored without refrigeration without becoming less effective (Kendall, 2013). While the vaccine will become ineffective if the patches come into contact with excessive moisture as moisture causes the vaccine to be released, this issue can be solved by properly sealing the patches. The nanopatch not needing refrigeration, as well as its compact size and extremely light weight, mean they are very easy and cheap to transport making rural areas more able to access vaccines and allowing vaccines to be transported around the world easily.
While vaccines with a needle and syringe currently need trained people to safely administer them the nanopatch is simply applied by pressing it onto the skin either with a finger or an applicator meaning they can be applied by anyone or even self-administered (Kendall, 2013). A lack of trained people is a serious issue in countries like South Sudan where 15 children died and 32 fell ill after they were given vaccines by people with improper training (Gharib, 2017). The nanopatch being easy to administer would prevent cases like this, and increase the number of people able to safely apply vaccines.
The World health organisation estimates that 1.3 million people die per year and 30% of vaccinations given in Africa are unsafe due to contaminated needles or needlestick injuries where unclean needles accidentally puncture the skin (Cooper, 2010) (Kendall, 2013). As Nano patches do not present these issues their use could prevent these deaths solving a serious social problem.
Another social issue, although more related to the first world, is that the pain involved with injections result in 10% of the population having needle phobia resulting in people actively avoiding getting immunized (Clemons, 2016). As previously mentioned, nanopatches are painless, unlike needles, meaning fewer people would avoid immunisation. A greater proportion of the population being immunized could decrease the prevalence of outbreaks of common preventable diseases such as influenza or measles.
The method by which we currently administer vaccines creates a large amount of sharps waste since a needle can only be used once before needing to be sterilized or disposed of. Sharps waste is extremely dangerous when not disposed of properly and can result in the previously mentioned needlestick injuries and contribute to the spread of diseases such as HIV and hepatitis (Queensland Government, 2012). Disposing of sharps waste can also be costly, discouraging proper disposal, and special facilities are required which poses a problem for developing countries and rural locations where these facilities are inadequate or unavailable (Levin Institute, 2010) (Sean, 2017). These problems are non-existent with the nanopactch due to its small volume and the micro projections not being long or sharp enough to be considered as sharps waste (Pearson et al., 2013). This is one of the unexpected advantages of the nanopatch.
Although not the indented purpose of the nanopatch they provide security to governments in the case of crisis. Due to the nanopatch’s light weight, ability to be self-administered and lack of a need to be refrigerated they could be sent out to homes in the event of a pandemic so populations could be protected against the rapidly spreading disease (ABC, 2012).