DNA vaccines work by introducing genetic material into cells that codes for an antigen, which stimulates an immune response against pathogens. They were first discovered in 1990 when injection of DNA plasmids produced an immune response in mice. Since then, DNA vaccines have been studied for various diseases and have advantages over traditional vaccines like not requiring refrigeration and inducing both antibody and cellular immunity. However, concerns remain around potential toxicity and more research is still needed before widespread human use.