Vaccines are undoubtedly the most important medical technology ever discovered, and since Edward Jenner first tested his smallpox vaccine in 1798, they have resulted in substantial decreases in disease morbidity and mortality. Vaccines have traditionally been made by isolating an infectious pathogen, weakening or inactivating it, and then administering it to face the human immune system. More complex vaccine development strategies have both advantages and disadvantages. Most importantly, they provide a way forward in areas where traditional approaches have failed.
The area of vaccination continues to evolve at a breakneck pace, with more effective and acceptable novel vectors and techniques making their way into clinical use. Along with the advancement of these new rationally designed vaccines, improved and more patient-acceptable delivery mechanisms are being developed to better target and sustain the pain-free injection of antigen. Because the majority of vaccines are still delivered with a hypodermic needle, either intramuscularly, subcutaneously, or intradermally, delivery is critical.