; (B) periodically review the list developed under paragraph (1) for continued necessity and appropriateness, and add, amend, or remove any classes or categories of drugs if no longer necessary or appropriate; and (C) maintain a publicly available archive of the list over time. (4) Transition period Before the date of the initial publication of the list developed under paragraph (1), the most recent priority list developed under this section before the date of enactment of the Prioritizing Medical Countermeasures for National Security Act of 2023 shall remain in effect. . (c) GAO report Section 565A of the Federal Food, Drug, and Cosmetic Act ( 21 U.S.C. 360bbb–4a ) is amended by inserting after subsection (g), as redesignated by subsection (b)(1), the following: (h) GAO report (1) In general Not later than September 30, 2027, the Comptroller General of the United States shall transmit to Congress a report on the effectiveness of this section in encouraging the development of the medical countermeasures needed to protect and prepare for emerging threats to public health and national security. (2) Contents The report shall include— (A) input from the Secretary of Defense and the Secretary of Health and Human Services; and (B) recommendations of the Comptroller General of the United States, if any, on necessary modifications to this section. . (d) Sunset Subsection (i) of such section, as redesignated by subsection (b)(1) of this section, is amended— (1) by striking subsection (b) and inserting subsection (c) ; and (2) by striking October 1, 2023 and inserting October 1, 2029 . (e) Conforming amendments To remove references to material threats Section 565A of the Federal Food, Drug, and Cosmetic Act ( 21 U.S.C. 360bbb–4a ) is amended by striking material threat each place it appears in— (1) subsection (a)(3); (2) paragraphs (1) and (2) of subsection (c), as redesignated by subsection (b)(1); and (3) subsection (f), as so redesignated.