For most of us, vaccinations are a normal, if not very pleasant, part of life. But what if there was an alternative? What if it was just as easy as putting on a sticking plaster? Researchers from Georgia Institute of Technology and Emory University reported in Nature Medicine this week that that might be closer to reality than we think.
Sean Sullivan and his colleagues have developed a patch that delivered an influenza vaccine to mice. They compared the effectiveness of this patch with a more traditional intramuscular vaccine and found that it protected mice equally as well against the otherwise lethal flu virus. Even more exciting, 90 days after vaccination, the patch-vaccinated mice were found to activate the immune response to influenza more promptly and to clear the virus more quickly from lung cells.
The patches each held 100 tiny needles just 650 microns long that dissolve painlessly from the patch into the skin, taking with them their load of freeze-dried deactivated influenza virus. Vaccinating in this way takes advantage of the skin's special immunological properties and may explain why the patch seemed to provide even better protection than the intramuscular method by some measures. Some drug patches are already in widespread use, for example nicotine and contraceptive patches but what distinguishes these new microneedle patches is that they are able to deliver much larger particles such as viruses, as opposed to just small molecules like nicotine.
This work offers an exciting glimpse of what vaccines could be like in the future. If we no longer rely on traditional intramuscular vaccination, the risk of spreading disease through the re-use of contaminated needles, which is a common problem in some developing countries, would be eliminated. In addition, the patches allow the vaccine to be given with little or no medical training making large-scale vaccination programmes cheaper and easier. And on top of all that, getting life-saving protection against many infectious diseases could soon be pain-free.