Maryland Code, Education § 3-13A-04

(b)(1) If a vacancy for a member occurs before the date that is 30 days before the date for filing a certificate of candidacy for the primary election in the presidential election year, the individual appointed under subsection (a) of this section shall serve only until a successor is elected by the voters at the next general election.

(2) Candidates for the vacated office may be nominated at a primary election in the same manner as for any other position on the county board.