General question about viruses

I apologize in advance if I am posting to the wrong forum.
I’ve tried Googling and surfing forums for the answer to my question and decided the best place to look will be a forum on an anti-virus site. I use aVast so here I am. All that said…
Can a virus, most specifically a boot virus, infect an exe file that I have not opened?
How would I prevent a virus, again most specifically a boot virus, from infecting a disk that I would be preparing to burn that contains the software that will eliminate said virus. It, the virus, shouldn’t write to the disk if it can’t get into a file or program right? Or will/can it?
As you may have guessed,I have something lurking in my MBR and I am planning to make it go away. So any info and good suggestions will help. I suspect that I may be performing similar operations on the rest of my families systems, so I pretty much need to perfect it on mine first.

Can only “work” if you run the execution able file/program.