"It has still not been confirmed with certainty that the inflammation was developed as a side-effect to the vaccination."
Post hoc ergo propter hoc. Is it absolutely unrelated? No, at this time we have no information either way. An investigation is being performed to see whether the vaccination is related in any way to the medical issues this teen is currently experiencing.
Anyone jumping to a conclusion about what this is or isn't related to before any investigation has been performed has an agenda.
Thank you