You have to catch the virus for vaccines to work.
Mill Worker
All vaccinations teach various type of immune system in your your body to recognise a disease causing agent, e.g. a virus so that it can be attacked next time.it is encountered. It sounds like you would agree with that.
But no vaccine prevents you catching a disease. The immune system is internal. So of course you need to internalise, that is catch, the virus for the immune system to start working in response. The whole point is that when you do catch the virus the trained immune system stops it multiplying as fast, keeping the infection to a manageable level. So you don't get ill - leaving the perception that you have not caught the virus. When in fact you did, but fought it off. Then as immune cells multiply in response to the infection, they overwhelm and eliminate the virus.
So these are just as much a vaccine as any other you have ever taken.