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

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.