Vaccines can be developed for bacterial or viral infections. As explained here the Centers for Disease Control and Prevention (CDC), vaccines are used to prevent, rather than treat, infection, “working with the body’s natural defenses to safely develop immunity to disease.” Vaccines mimic an infection, causing the body to produce antibodies and defensive white blood cells, in order to help develop immunity.
https://www.reuters.com/article/world/fact-check-vaccines-do-protect-against-viral-infection-idUSKBN25O207/