So, why has the CDC been lying about this for the last two years and insisting that the mRNA “stays in the arm?” Well, the obvious answer is that the idea of the mRNA staying at the injection site is reassuring, since otherwise we could fear systemic adverse effects of precisely the sort that have emerged since rollout.

https://brownstone.org/articles/cdc-lied-mrna-not-meant-to-stay-in-arm/?