They know why. MRI machines make incredibly powerful magnetic fields.
Humans are not harmed by this unless they have some form of magnetically permeable material in them.
Say for instance nano particles of some metal that is in the covid vaccine for some silly reason.
~Easy
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Other problem is that the jab can affect the lymph nodes on the same side as the jab was on; scanning (I don’t remember which modality) then shows the lymph nodes looking abnormal similar to early pre-cancerous / early breast cancer stages.