Scientists have developed a pain-free injection system to immunise people against influenza. Writing in the current edition of PNAS, Emory University researcher Richard Compans and his colleagues describe how a system of microneedles, each measuring less than a tenth of the diameter of a traditional small hypodermic needle and designed just to penetrate the surface of the skin, can be used to protect mice against fatal
The needles are then allowed to dry, in which form they are chemically stable, and may then be kept until needed. Vaccination is achieved by pressing the needles against the skin,which transfers the virus material from the needles. Tests on mice showed that within fourteen days the animals produced equivalent levels of antibodies to a test vaccine as animals that received traditional intramuscular flu injections. The team were also able to protect mice against a potentially fatal infection with a strain of influenza that killed unimmunised, control animals.
The system works by exploiting the relatively large number of so-called professional "antigen presenting cells" (APCs) including Langerhans and dendritic cells which are present in the skin.These take up the injected materal and encourage the immune system to mount a response. And for inoculations that require larger doses of vaccine