The researchers began by studying materials that could be combined with the vaccine to improve its stability in dry form. Ultimately, they obtained the best results by adding a sugar known as trehalose to the liquid vaccine. That formulation was applied to the microneedles which were about 750 microns long by dipping them into the solution and allowing the liquid to dry. The vaccine dose on the microneedles was controlled by the number of times the microneedles were dipped into the solution.
Cotton rats (Sigmodon hispidus) used in the study were divided into seven groups of five animals each for the testing. The comparison showed that vaccination with the microneedle technique produced an immune response that was statistically indistinguishable from that produced by vaccination with the hypodermic needles.
"The two major accomplishments of this study are that the vaccine can be stabilized on microneedles, and that it could dissolve in the skin to provide a good immune response," Rota said.
To advance the microneedle technique, the researchers are now working to improve the stability of the dry vaccine with the goal of eliminating the need for refrigeration. They are also studying the use of polymer-based microneedles that would fully dissolve in the skin, removing the need to dispose of potentially infectious waste.
Ultimately, a microneedle-based measles vaccine will need to be evaluated for safety and efficacy in a non-human primate model and in several clinical trials before it can be used routinely in humans.
Microneedles are also being studied for administration of vaccines against influenza, polio, rotavirus, tuberculosis, and hepatitis B. The microneedle
|Contact: John Toon|
Georgia Institute of Technology Research News