Hi, thank you for your thoughtful comments. Yes, I think you are right that the mRNA is gone from the body after a few days max. However, depending on the type of protein, protein expression may last longer than mRNA expression.

But, luckily, the luciferase protein expression studies show that the protein expression of the LNP-encapsulated mRNA vaccine lasts for a few days too.

From what I understand, the rough ingredients in the LNP formulation is made public. But the specific formulation - i.e., how the final chemical structure looks like - is unclear, if not unknown. On second thought, however, I think the specific LNP formulation may not be an important piece of info, as long as the toxicology studies in animals deem the LNP formulation as safe.

Thus far, I'm not aware of any studies in humans that looked at the biodistribution of the mRNA vaccine. I think such human studies are unethical because that would involve repeated invasive tissue sampling, if not autopsies. It also doesn't seem ethical either to inject luciferase-encoding mRNA vaccine into humans to just see where the luciferase expression lights up when such experiments have been done in animals.