What parts of the immune system can potentially be stimulated by a vaccine?

: •What parts of the immune system can potentially be stimulated by a vaccine? •What do those immune system components do (different Ab classes, different T cells etc)? •In what fundamental ways do those aspects of the immune system differ from other aspects (say innate or barrier) •What is the proof that vaccines are useful? •What is the concept of herd immunity and how can vaccines contribute to that? •What are some of the forms a vaccine could take: live, killed, vectored etc? •