Yeah people would be dying a lot faster if you put cobalt in there.

But I was reading about ferritin. Not only is it involved in immune response..

Ferritin concentrations increase drastically in the presence of an infection or cancer. Endotoxins are an up-regulator of the gene coding for ferritin, thus causing the concentration of ferritin to rise. By contrast, organisms such as Pseudomonas, although possessing endotoxin, cause plasma ferritin levels to drop significantly within the first 48 hours of infection. Thus, the iron stores of the infected body are denied to the infective agent, impeding its metabolism.

But its being used in the production of some nanoparticles used in something called Spycatcher/spytag vaccine technology.

By fusing either SpyTag or SpyCatcher to self-assembling molecules such as virus-like particles, antigens fused to the other pair can be decorated onto the molecule via the isopeptide bond formed.[10][11][12][13] This enables fast production of vaccines as the central self-assembling molecule can be stocked up beforehand, whilst the antigen can be easily produced under optimal conditions to achieve proper protein folding.

Just shit I pulled of wikipedia. But you might be on to something. You wouldn’t thing there would be enough iron in the ferritin to make a frige magnet stick but I dont know!