Once the vaccine mRNA is in the cytoplasm its used to make the SARS-CoV-2 spike protein.The vaccine mRNA is short-lived and is rapidly broken down after its done its job, as happens with all your other mRNA.Heres why the mRNA cant insert into your genetic code Your genetic code is made up of a different, but related, molecule to the vaccine mRNA, known as DNA, or deoxyribonucleic acid.