Similar to live-attenuated viral vaccines, these bacterial vaccines are more effective at eliciting protective immunity because the attenuated bacteria can continue to replicate in order to mimic a real bacterial infection. Although there is still ongoing research to produce new live-attenuated bacterial vaccines, the number remains relatively small.

Ex:

• Bacille Calmette-Guérin (BCG) Vaccine

• Salmonella typhi Vaccine