Reasons related to non-vaccination and under-vaccination of children in low and middle income countries: findings from a systematic review of the published literature, 1999-2009.

Objective: Despite increases in routine vaccination coverage during the past three decades, the percent of children completing the recommended vaccination schedule remains below expected targets in many low and middle income countries. In 2008, the World Health Organization Strategic Advisory Group of Experts on Immunization requested more information on the reasons that children were under-vaccinated (receiving at least one but not all recommended vaccinations) or not vaccinated in order to develop effective strategies and interventions to reach these children.

Methods: A systematic review of the peer-reviewed literature published from 1999 to 2009 was conducted to aggregate information on reasons and factors related to the under-vaccination and non-vaccination of children. A standardized form was used to abstract information from relevant articles identified from eight different medical, behavioural and social science literature databases.

Findings: Among 202 relevant articles, we abstracted 838 reasons associated with under-vaccination; 379 (45%) were related to immunization systems, 220 (26%) to family characteristics, 181 (22%) to parental attitudes and knowledge, and 58 (7%) to limitations in immunization-related communication and information. Of the 19 reasons abstracted from 11 identified articles describing the non-vaccinated child, 6 (32%) were related to immunization systems, 8 (42%) to parental attitudes and knowledge, 4 (21%) to family characteristics, and 1 (5%) to communication and information.

Conclusions: Multiple reasons for under-vaccination and non-vaccination were identified, indicating that a multi-faceted approach is needed to reach under-vaccinated and unvaccinated children. Immunization system issues can be addressed through improving outreach services, vaccine supply, and health worker training; however, under-vaccination and non-vaccination linked to parental attitudes and knowledge are more difficult to address and likely require local interventions.