Vaccines are a crucial tool in preventing the spread of infectious diseases. They work by stimulating the immune system to recognize and fight off specific pathogens. Vaccines can be designed using several different approaches, such as using weakened or inactivated viruses or bacteria, or synthetic versions of specific antigens. Some vaccines also contain adjuvants, which enhance the immune response to the antigen. Regular vaccination schedules are important for maintaining immunity against diseases and preventing outbreaks in the population.