A vaccine in the form of a skin patch has proved more effective than a needle in mice.
Scientists tested the patches on a group of mice, comparing the results with mice immunised using a traditional syringe. A month later both groups were infected with influenza and dealt with the virus well. But the mice with the patches were better able to cope with a second flu infection three months after vaccination.
The vaccine is effective because there are important immune cells within the skin. These cells form a special network that immediately recognises foreign particles (antigens) which are present in vaccines, making the skin a good site for inoculation. The patch is made of biodegradable microneedles, each about six times the thickness of a human hair. Every microneedle is coated with the flu vaccine and dissolves away within minutes after contact with the skin. The new patch vaccine builds on earlier skin vaccine technology developed in the mid 1990s and the testing of microneedle delivery using proteins, nanoparticles and other small molecules.
Skin patches eliminate the need for trained healthcare workers to give the vaccine. Developing countries would not need a costly medical infrastructure. Peoplecould send off for the patch or obtain it at their nearest clinic and administer the vaccine themselves. It is cost effective, convenient and overcomes the biohazard of ‘dirty’ needles and medical waste.
The microneedles are made of the plastic polyvinylpyrrolidone. This material is already being used in medical equipment without any side effects, but the team will need to complete further trials before the patch is tested in humans.