> Given the central role of RNA in many fundamental biological processes, including translation and splicing, changes to its chemical composition can have a detrimental impact on cellular fitness, with some evidence suggesting that RNA damage has roles in diseases such as neurodegenerative disorders. We are only just beginning to learn about how cells cope with RNA damage, with recent studies revealing the existence of quality-control processes that are capable of recognizing and degrading or repairing damaged RNA.
How does it recognize corruption? Certainly some could be processed with incomplete or incorrect results. It's really hard (probably impossible) to show that there will not be negative effects from that.
Valid mRNA has a start codon and a stop codon. Without these mRNA will be broken down and untranslated. However without translation the vaccine will be useless. So while unintended translation is unlikely it is possible that efficacy would be impacted.
Mitochondria won't decode the corrupted mRNA and it will be broken down into constituent parts that are reused by the body.
Edit: Oops, ribosomes, not mitochondria.