MRNA isn't a vaccine. MRNA is a medical platform or type of technology that can be programmed to do many things. MRNA programming your cells to produce spike proteins is not the same as your body fighting off dead or partial fragments of viral materials. It's just not the same, this type of therapy is usually called gene therapy and mostly seemed to be before covid, because MRNA tells your cells to produce spike proteins, where the MRNA wrapped in lipid nanoparticles itself doesn't provide any immunity from anything, because it's a piece of designed biotechnology.
When you inject a traditional vaccine, your immune system fights what's immediately injected into you to gain immunity, antibodies, whatever the aimed response is.
With MRNA "vaccines", MRNA is injected and goes into your cells, hijacks your cell's ribosomes, and then your cell starts producing it's own spike proteins, which are very toxic and cause health problems, but the idea is to get immunity from the spike proteins, but the way immunity is theoretically obtained is by biomedical technology hijacking your cell's function to produce spike proteins. That's absolutely nothing like how a traditional vaccine works.