; or (II) is experimental or investigational, but is furnished as part of a clinical trial that meets the standards of coverage applicable under any national coverage determination relating to clinical trials. (B) Significant coverage The Secretary shall through notice-and-comment rulemaking establish requirements for what constitutes coverage of an item or service under a significant number of group health plans and group or individual health insurance coverage in a State or jurisdiction. Such requirements may provide that such significant number is demonstrated through a showing that a majority of similarly situated individuals covered under such a plan or group or individual health insurance coverage in such State or jurisdiction would have benefits available under such plan or coverage for such item or service or through such other similar metrics determined appropriate by the Secretary. (4) Duration (A) In general The program shall be in effect for a period of not less than 4 years. (B) Expansion The Secretary may, during the period in which the program is in effect and as determined appropriate by the Secretary, expand the program to additional States or jurisdictions not originally selected under paragraph (2). (C) Termination The Secretary may terminate the program— (i) only on or after the date that is 4 years after the effective date of the program; and (ii) only once the Secretary has concluded a 60-day public comment period with respect to such termination. .