Disease X Act of 2023 This bill expands the priorities of the Biomedical Advanced Research and Development Authority (BARDA) to specifically include viral threats that have the potential to cause a pandemic. In particular, the bill expands the scope of innovation grants and contracts that may be awarded by BARDA to specifically include those that support research and development of certain manufacturing technology for medical countermeasures against viruses, including respiratory viruses, with pandemic potential. It also expands BARDA's authorized strategic initiatives to include advanced research, development, and procurement of countermeasures and products to address viruses with pandemic potential.