42 C.F.R. § 21.52
If, in time of war or national emergency proclaimed by the President, the Secretary determines that there is need for commissioned personnel to meet the needs of the Service, other than persons eligible for examination for original appointment under the eligibility requirements prescribed in this subpart, he may prescribe standards of eligibility for examination for the original appointment of officers in the Reserve Corps without regard to such eligibility requirements. Such standards shall, however, authorize the examination only of candidates with specialized experience in administration or management or candidates with training or experience in fields relating to public health. The permanent grade of an officer who becomes eligible for examination for appointment pursuant to such standards and who becomes eligible for appointment after passage of an examination shall be limited to the junior assistant or the assistant grade, except that, if upon examination a candidate is found to be exceptionally qualified for the performance of highly specialized duties with the Service pursuant to § 21.55 , he may be recommended for appointment to any grade up to and including the director grade.
42 C.F.R. §21.52