Shrek: No. Layers. Onions have layers. Ogres have layers. Onions have layers. You get it? We both have layers.
Instead of a single immune response, the human immune system can be though of as having several layers of immune response, that all fade at different rates.
Immunity is a complex set of different layers all subject to change over time at varying rates, making comparison between immunity following vaccination or infection highly time dependant.