For accident and health insurance contracts issued on or after the operative date of the valuation manual designated in subsection (2) of section 44-8908, the standard prescribed in the valuation manual is the minimum standard of valuation required under section 44-8904. For disability and sickness and accident insurance contracts issued on or after the operative date defined in section 44-407.07 and prior to the operative date of the valuation manual, the minimum standard of valuation is the standard adopted and promulgated by the director by rule and regulation.