When a communicable disease exists in or near the community to the extent that an epidemic exists or may develop, and the health officer deems the situation an emergency, he or she may provide that persons who cannot provide evidence of effective immunity naturally or artificially induced against such disease shall not be permitted to attend any school or other public gathering. In such an emergency it shall be the duty of the health officer to immunize all persons who are unable to employ a private physician and to expedite the immunization of all persons through mass procedures if, in the opinion of the health officer, such mass procedures are indicated. A person shall be deemed unable to employ a private physician if he or she states that he or she are unable to employ a private physician.