Table 2 The results of explanatory factor analysis (n = 400), Cronbach’s alpha (n = 100), ICC (n = 30) and AVE and AR (n = 400)

Low knowledge

1. Polio and measles vaccines cannot prevent two measles and poliomyelitis diseases in children.

2. Polio and measles vaccines have no benefit for children.

3. Polio and measles vaccines are harmful for children.

4. It is not necessary for children who were born in Iran and have already received all their vaccines to receive supplementary polio or measles vaccines.

5. Before migrating to Iran, my child had already been vaccinated against polio and measles. I don’t think it is necessary for them receive the vaccinations again in Iran.

Negative attitude

7. Migrants who enter a country illegally may be afraid to go to health centers to have their children vaccinated against polio or measles.

8. The aim of polio and measles vaccination is to test the vaccines on the children of the migrants.

9. Polio and measles vaccination aim for the children of the migrants is gene change of the migrants.

10. When polio or measles vaccines are given only to migrants children and not to Iranian children, it is suspicious.

11. As children, we did not receive vaccinations for polio or measles and never became sick. Therefore, why should our children receive vaccinations?

Low participation in vaccination programs

12. I don’t know the health liaison for my place of residence.

13. I don’t know how to provide my opinions and suggestions to health officials and providers to increase the coverage of polio and measles vaccination in the children of migrants and refugees.

14. So far, I have not received any counseling or training on the importance of vaccinating children against polio and measles.

15. So far, I have not been invited to participate in the implementation of polio and measles vaccination programs for children of migrants and refugees.

16. The lack of educational programs in our mother tongue and languages (Dari, Uzbek, Pashto, Tajik, Arabic, Urdu, etc.) causes me to be indifferent towards polio and measles vaccination programs.

Communication challenges

17. I have heard from others that after vaccination for polio, some children become paralyzed.

18. People around me, considering their negative experiences, have asked me not to do polio and measles vaccination for my children.

19. Migrants who have recently arrived in Iran do not trust the recommendations of Iranian health providers to vaccinate their children against polio or measles.

20. Living on the outskirts of cities and remote areas can hinder or delay the vaccination of my children against polio and measles.

21. My spouse or mother-in-law does not allow me to leave the house to get my child vaccinated.

Problems related to migration and refugee

22. My place of residence and my family’s address in Iran frequently change.

23. I don’t have my child’s previous vaccination card, and I don’t know which one of my children has not received their vaccines.

24. The busyness of life and migration prevent me from timely taking my child for vaccination.

25. Due to my unfamiliarity with Iran, I cannot remember my home address accurately and record it in the health file. As a result, healthcare workers cannot find our house for my child’s vaccination.

26. My child does not have a birth certificate, and I do not know their age.