Miss. Code Ann. § 37-7-204

In the event that a vacancy occurs in the office of any elected trustee of a countywide municipal separate school district, and the next regular school board election at which the vacancy may be filled is less than one (1) year from the date of the resignation, the school board of the district may, in its discretion, take action to appoint an interim board member to fill the vacancy until a duly qualified successor takes office. The interim board member shall serve until such time as the successor board member is duly elected to fill the unexpired term, pursuant to an election held at the next regularly scheduled school board election held in the county.