If DNA is a blueprint, mRNA is a photocopy that's used as a working memory of it for a ribosome to use while making a protein. It's chemically unstable and soon

If DNA is a blueprint, mRNA is a photocopy that's used as a working memory of it for a ribosome to use while making a protein. It's chemically unstable and soon falls apart. (The individual nucleotides night be recycled into other mRNA strands that the cells make.) Since the vaccine mRNA does not have any corresponding DNA to make more copies from, that's the end of it.