Changes

'''Disadvantages'''

'''Disadvantages'''

*The host's immune system needs to evoke an immune response against the antigen which can take a few days

*The host's immune system needs to evoke an immune response against the antigen which can take a few days

*Can require two or more doses to be effective; the first dose initiates the '''priming''' reaction where [[Immunoglobulins|antibody]] production ceases after a few weeks, but the second and subsequent doses create [[B cell differentiation#Memory cells|memory cells]] which remain in the circulation for a much longer period of time

*Can require two or more doses to be effective; the first dose initiates the '''priming''' reaction where antibody production ceases after a few weeks, but the second and subsequent doses create memory cells which remain in the circulation for a much longer period of time.

==Vaccine Antigens==

==Vaccine Antigens==