1. If a governing body, a county board of supervisors, or a city council has procured for its employees accident, health, or hospitalization insurance, or a medical service plan, or has contracted with a health maintenance organization authorized to do business in this state, the governing body, county board of supervisors, or city council shall allow its employees who retired before attaining sixty-five years of age to continue participation in the group plan or under the group contract at the employee’s own expense until the employee attains sixty-five years of age.
 2. This section applies to employees who retired on or after January 1, 1981.