In any county with a board of retirement composed of nine members pursuant to Section 31520.1, if the second, third, seventh, or alternate seventh member of the board is injured or killed while performing his or her duties as a member of the board, that member shall be deemed to have been acting in the course and scope of his or her duties as an employee of the county or district employing the member, for the limited purpose of

determining eligibility for workers’ compensation benefits or disability or death benefits from the retirement system.

This section shall not be operative in any county until the board of supervisors, by resolution adopted by a majority vote, makes this section operative in that county.