A) Questionnaire
The questionnaire consisted of three parts:The first part of the questionnaire: includes 21 questions related to knowledge of immunization, which for each correct answer was assigned a score of 1 and otherwise a score of 0. The maximum score for this section was 21.The second part of the questionnaire: includes 6 questions related to the attitude towards Immunization, which is designed based on the 5 Likert scales (strongly agree, agree, have no opinion, disagree, and strongly disagree). The maximum score was 30 and the minimum was 6.The third part of the questionnaire: Self-efficacy questions related to the vaccination ability that includes 9 questions based on the 5 Likert scales (strongly agree, agree, have no opinion, disagree, and strongly disagree). Scores ranged from 9 to 45.The content validity method was used to test the validity of the questionnaire. Thus, the questionnaire was prepared based on the instructions of the Iran Ministry of Health then its content was inspected by 2 faculty members of the School of Health and the necessary corrections were considered. To evaluate the reliability of the questionnaire, so the questionnaire was completed by 30 students and Cronbach’s alpha was determined as 0.76 for knowledge, 0.72 for attitude and 0.76 for self-efficacy, and 0.75 for the whole questionnaire. Questionnaires were designed and completed online using Google Docs.