Getting vaccinated against diseases is part of living in the modern world, and as the fight against HIV, TB and malaria continues, scientists are under increasing pressure to produce a cheap yet effective way of manufacturing and delivering vaccines. Thanks to a new technological advance made by researchers at King’s College London, there may be a solution to delivering a vaccine without the use of traditional needles. But why is this important?
Hypodermic needles carry the risk of contamination, and most live vaccines have to be stored at a temperature of between 2°C to 8°C or below, to ensure the effectiveness and safety of the live vaccine. Researchers at the London College have managed to deliver a dried live vaccine to the skin without a traditional needle, and not only this, but they have demonstrated that this technique is powerful enough to enable specialised immune cells in the skin to kick-start the immunising properties of the vaccine.
The study, which was funded by the Bill & Melinda Gates Foundation, has been published today in Proceedings of the National Academy of Sciences, and although researchers say it is an early study, it could be a potential break through regarding the many challenges of delivering live vaccines in resource-limited countries globally, all without the need for refrigeration.
The researchers at the London College used a silicone mould developed by US company TheraJect to create a microneedle array. This tiny disc contains micro-needles made of sugar which dissolve when inserted into the skin. The team formulated a dried version of a live modified adenovirus-based candidate HIV vaccine in sugar (sucrose) and used the mould to create the microneedle array. They found that the dried live vaccine remained stable and effective at room temperature, which removed the need to keep the live vaccine at a refrigerated temperature.
Mice were used to test the effectiveness of the microneedle array. Results showed that in trials, the vaccine dissolved in the skin and the researchers were able to identify for the first time exactly which specialised immune cells in the skin ‘pick up’ this type of vaccine and activate the immune system. This is the first time that evidence has shown a sub-set of specialised dendritic cells in the skin were responsible for triggering this immune response.
And when the researchers compared these results with a traditional needle vaccine method, the immune response generated by the dried microneedle vaccine (kept at room temperature) was equivalent to that induced by the same dose of injected liquid vaccine that had been preserved at -80°C.
Dr Linda Klavinskis from the Peter Gorer Department of Immunobiology at King’s College London, said: “We have shown that it is possible to maintain the effectiveness of a live vaccine by drying it in sugar and applying it to the skin using microneedles – a potentially painless alternative to hypodermic needles. We have also uncovered the role of specific cells in the skin which act as a surveillance system, picking up the vaccine by this delivery system and kick-starting the body’s immune processes.” She added: “This work opens up the exciting possibility of being able to deliver live vaccines in a global context, without the need for refrigeration. It could potentially reduce the cost of manufacturing and transportation, improve safety (as there would be no loss in potency), and avoids the need of hypodermic needle injection, reducing the risk of transmitting blood-borne disease from contaminated needles and syringes.”