Here's the product page. Stop making this about the goddamn vaccine, it has nothing to do with it.
This is peak fearmongering fake news, all of you should know better than to share this garbage.
https://www.particle-works.com/product-category/magnetic-particles/iron-oxide-coated-cobalt-particles/
Oxidatively Stable Cobalt Nanoparticles
Oxidatively stable cobalt nanoparticles with maximized magnetic performance. A monodisperse cobalt core and a magnetite shell of 1-2 nm thickness.
https://www.particle-works.com/product-category/magnetic-particles/iron-oxide-coated-cobalt-particles/