Measles Vaccination With Microneedle Patch
New delivery technique could revolutionize immunization programs, researchers say (Nov. 27)
The measles vaccine, when given with microneedle patches, can immunize against measles at least as well as vaccine given with conventional hypodermic needles, according to research conducted by the Centers for Disease Control and Prevention (CDC) and the Georgia Institute of Technology.
In the new study, the researchers developed a technique to dry and stabilize the measles vaccine — which depends on a live attenuated virus — and showed that it remained effective for at least 30 days after being placed onto the microneedles. They also demonstrated that the dried vaccine was quickly released in the skin and able to prompt a potent immune response in animals.
The microneedle technique could provide a new tool for international immunization programs against measles, which killed nearly 140,000 children in 2010, according to the researchers. The study was reported online in the journal Vaccine.
Current measles immunization programs use conventional hypodermic needles to deliver the vaccine. Large global immunization programs therefore require significant logistical support because the vaccine must be kept refrigerated; large numbers of needles and syringes must be shipped; and the ten-dose vaccine vials must be reconstituted with sterile water before use.
The use of microneedle patches could eliminate the need to transport needles, syringes, and sterile water, reducing logistical demands, the researchers say. Vaccination could be done by personnel with less medical training, who would simply apply the patches to the skin and remove them after several minutes, making possible door-to-door campaigns similar to those used in polio vaccination. Single-use patches could also reduce the waste of vaccine that occurs when all ten doses in a vial cannot be used.
In their study, the researchers first faced the challenge of converting a liquid vaccine to a formulation that could be readily applied to stainless steel microneedles and dried for packaging. The work was made more difficult by the fact that the vaccine contains an attenuated live virus whose integrity had to be maintained.
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 the sugar 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.
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 the administration of vaccines against influenza, polio, rotavirus, tuberculosis, and hepatitis B. The microneedle measles vaccine would likely find its first use in the developing world as part of measles elimination campaigns, and would probably not replace the measles–mumps–rubella (MMR) vaccine used in the U.S.
Source: Georgia Institute of Technology; November 27, 2012.