The department, to the extent permitted by law, is authorized to pay employees who are exempt or not exempt for purposes of the Fair Labor Standards Act of 1938 (29 U.S.C. § 201 et seq.) on a straight-time basis for work on a holiday or for regular compensatory time hours when the taking of regular compensatory time off would be disruptive to normal business operations. Authorization for payment under this section is limited to work directly related to immunizations.