After taking the vaccine, does it wear off? Does your immune system return to normal? Does the override cease?
Why has there not been an old style vaccine consisting of the weakened virus which your immune system would attack naturally?
Old-style vaccines are practically ineffective for RNA based viruses, because those viruses have poor replication integrity, leading to rapid changes in structure. For that reason, the virus may not have enough in common with its ancestor, the original target of the vaccine, to be recognized by the immune system. In a nutshell...
See post 92 video.