comments and within 90 days of the close of the comment period, the Secretary shall issue a final order adopting the proposed standard, adopting a modification of the proposed standard or terminating the proceeding. (d) Amendment process The procedures established in this section or in guidance issued under this section shall apply to amendment of an existing standard. 587R. Investigational use (a) In general Except as provided in subsection (c), an in vitro clinical test for investigational use shall be exempt from the requirements of this subchapter other than sections 587A, 587O, and 587U. (b) Regulations Not later than 2 years after the date of enactment of the Verifying Accurate Leading-edge IVCT Development Act of 2020 , the Secretary shall promulgate regulations to implement this section. (c) Application for investigational use (1) In general The following shall apply with respect to in vitro clinical tests for investigational use: (A) Streamlining applications submitted under this section Requirements with respect to such tests shall be completed in accordance with current investigational use requirements for institutional review boards and current processes for any analytical or clinical validation. (B) Variation The requirements in the regulations promulgated under this section shall take into account variations based on— (i) the scope and duration of clinical testing to be conducted under investigation that is the subject of such application