To encourage expeditious development and deployment of medical countermeasures during a public health emergency, the PREP Act authorizes the Secretary of HHS (the Secretary) to limit legal liability for losses resulting from the administration of medical countermeasures such as diagnostics, treatments, and vaccines. In a declaration effective February 4, 2020 (the PREP Act Declaration), the Secretary invoked the PREP Act and declared COVID-19 to be a public health emergency warranting liability protections for covered countermeasures. Pursuant to the PREP Act Declaration and its subsequent amendments, manufacturers, distributors, and health care providers are generally immune from legal liability (i.e., they cannot be sued for money damages in court) for losses related to the administration or use of covered countermeasures against COVID-19.$Pfizer(PFE)$