Earlier quoted context omitted.
I had assumed the vaccine was also intended/believed to induce T-cell response, is that not the case? Given that they disappear within a matter of months after a natural infection, how long are the antibodies from the vaccines believed to last?
Oh, it is. I meant that that is also part of 'natural' immunization. The distinction between the 'natural' exposure and the vaccine is that the natural exposure targets a number of epitopes, which may or may not include effective neutralizing antibodies against the spike protein; the vaccine, on the other hand, only offers the spike as an antigen, so you know you're generating neutralizing ab.
There are vaccines in development that also target the N-protein.