The biggest issue involving Federalism

Think of vaccine mandates, probably the biggest issue involving federalism in the past several years. Constitutionally, are vaccine mandates part of a state’s power or the federal government’s? How do we know? In your opinion, whose power should they be? What about cities: in your opinion, should they have the right to impose mask mandates? Why or why not? (NOTE: That’s really 5 questions, but they’re easy, so be sure you answer them all, even if briefly.)