A DNA vaccine is a type of vaccine that uses genetically engineered DNA to stimulate an immune response. Instead of using weakened or inactivated pathogens, DNA vaccines introduce a small, circular piece of DNA called a plasmid into the body. This DNA contains instructions for cells to produce a harmless part of a virus or bacterium, prompting the immune system to recognize and fight the actual pathogen if encountered in the future. These vaccines are considered promising because they can be developed quickly and are stable at room temperature, making them easier to store and transport. DNA vaccines have been researched for various diseases, including HIV, Zika virus, and COVID-19, showing potential in both animal studies and human trials.