[bun_at_work]

https://www.youtube.com/watch?v=zQGOcOUBi6s

Here's a nice video on the immune system that might help you out. Their other videos on the immune system, the complement system, and viruses might also be helpful. Not the most technical deep dives, but good, abstracted explanations.

In short, I don't think the vaccine prevents entry of the virus into the cells. That still happens, as it's a mechanical protein interaction (as far as I know). However, the vaccine (mRNA ones at least) work by producing the protein on the outside of the virus and putting that in your system, so your immune system learns how to respond. At least that's my mile-high interpretation.