In the event of an emergency declared by HHS, Federal law would preempt all state provisions related to pandemic emergency preparedness, and would supersede any state provision governing vaccines. PREPA applies to any drug, vaccine, or biological product that the HHS secretary deems a "covered countermeasure," or that the secretary decides is a public health situation that could become an emergency at some point in the future, whether or not there is a specific relationship to a dangerous pandemic or bioterrorism.