An mRNA vaccine slips into your cells via some lipid nano particles, a ribosome binds to it manufacturing and releasing COVID spike proteins. This provokes an immune response. Does not enter the nucleus, or touch your DNA.
Reverse transcription is a real biological process. We can’t rule it out in the human body. We don’t have enough experience to be sure. If this was the Black Death, the risk would be justified. It might be justified here for people above child rearing age. But fertile people need to be more careful with their genetics.
