What makes up a vaccine?

A vaccine typically contains an antigen, which is a weakened or inactivated form of a pathogen (virus or bacterium) or a piece of its genetic material, to stimulate an immune response. It may also include adjuvants, which enhance the immune response, and stabilizers or preservatives to maintain the vaccine's efficacy and shelf life. Additionally, some vaccines may contain trace amounts of other substances used during manufacturing. Together, these components work to prepare the immune system to recognize and combat the actual pathogen if encountered in the future.