Vaccines developed traditionally… often limited problems of immunogenicity, probably due to the low level of purity of the active component(s) they contain. The application of new technologies to vaccine development is leading to the production of purer… antigens which, however, tend to have a poorer immunogenicity…
The development of… new vaccine adjuvants has been hampered by their [unacceptable] reactogenicity [adverse reactions].
Cholera toxin (CT) and labile enterotoxin (LT) mutants given along with intranasal or oral vaccines are strong candidates as mucosal adjuvants. Their potential reactogenicity is still matter of discussions…
[A]djuvanticity is more often evaluated in terms of antigen-specific antibody titers induced after parenteral immunization. It is known that, in many instances, antigen-specific antibody titers do not correlate with protection.