Anything magnetic and “nano” in size in the vaccine would be filtered out by the steel needle, as it would all adhere to it, as it travels down, into the body.
Every needle would be plugged solid.
Needles are stainless steel, which is non-ferrous and is not attracted to magnets.
Stainless steel (needles) is nonmagnetic.
Magnets won’t stick to stainless steel.