KING’S COLLEGE LONDON (UK) — A technique that delivers a dried live vaccine to the skin without a traditional needle could support the global fight against diseases such as HIV and malaria.
The new method requires no refrigeration and is less expensive and less painful compared to using hypodermic needles. It would also remove safety risks from needle contamination.
HIV, malaria, and tuberculosis represent major global health challenges. Although promising research is under way to develop vaccines, considerable stumbling blocks remain for countries where transporting and storing live vaccines in a continuously cold environment (around 2°C to 8°C or below) would not be possible. If a cold chain cannot be maintained for a live vaccine, there is a high risk it could become unsafe and lose effectiveness.
As reported in the Proceedings of the National Academy of Sciences, researchers used a silicone mold to create a microneedle array—a tiny disc with several needles made of sugar that 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 mold to create the microneedle array. The dried live vaccine remained stable and effective at room temperature.
To test the vaccine’s effectiveness, they gave it to mice. The team observed how the vaccine dissolved in the skin and identified for the first time exactly which specialized immune cells in the skin “pick up” this type of vaccine and activate the immune system—the first evidence that a subset of specialized dendritic cells in the skin are responsible for triggering the immune response.
When compared with a traditional needle vaccine method, the immune response generated by the dried microneedle vaccine that was kept at room temperature was equivalent to that induced by the same dose of injected liquid vaccine that had been preserved at -80°C.
“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,” says Linda Klavinskis from the immunobiology department at King’s College London. “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.
“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.
“The new technique represents a huge leap forward in overcoming the challenges of delivering a vaccination program for diseases such as HIV and malaria. But these findings may also have wider implications for other infectious disease vaccination programs, for example infant vaccinations, or even other inflammatory and autoimmune conditions such as diabetes.”
Source: King’s College London