An injection of killed or attenuated Salmonella typhi, the causative agent of typhoid fever, would be expected to protect an individual by- providing the individual with the premade antibodies capable of binding to and inactivating salmonella typhi- causing the individual to have a mild case of typhoid fever, but protecting against future cases of typhoid fever- providing cross- protection to prevent several diseases caused by different bacteria- providing antigens recognizable by the immune system, allowing the formation of memory cells that will prevent typhoid fever in the future
