Live attenuated virus, dead virus, virus parts, all require cloning or otherwise manufacturing virus.
That might require growing them in some type of host animal or bacteria.
Working with cell-colonies is a pain, messy, slow, costly.
mRna means you are using the person to produce the specific material you are after.
Skips a big step in manufacturing.
Dna/Rna are really easy to work with and create exactly what you want and clone/amplify it.
You don't need big bacterial cell culture batches, growth media, nutrients, worry about contamination, all of which is difficult/expensive/time consuming to work with.
No, instead, now the human is the fucking toxic particle factory.

Live attenuated virus, dead virus, virus parts, all require cloning or otherwise manufacturing virus. That might require growing them in some type of host animal or bacteria.
mRna means you are using the person to produce the specific material you are after. Skips a big step in manufacturing. Dna/Rna are really easy to work with and create exactly what you want and clone/amplify it.
You don't need big bacterial cell culture batches, growth media, nutrients, worry about contamination, all of which is difficult/expensive/time consuming to work with.
No, instead, now the human is the fucking toxic particle factory.

Live attenuated virus, dead virus, virus parts, all require cloning or otherwise manufacturing virus. That might require growing them in some type of host animal or bacteria.
mRna means you are using the person to produce the specific material you are after. Skips a big step in manufacturing. Dna/Rna are really easy to work with and create exactly what you want and clone/amplify it.