Effective interventions to increase routine childhood immunization coverage in low socioeconomic status communities in developed countries: A systematic review and critical appraisal of peer-reviewed literature.

Objectives: Childhood immunization coverage rates are known to be disproportionate according to population's socioeconomic status (SES). This systematic review examined and appraised quality of interventions deemed effective to increase routine childhood immunization uptake in low SES populations in developed countries.

Methods: A literature search was conducted using Medline, Embase, CINAHL, EBMR, PsycInfo, PubMed, and Health STAR. We systematically searched and critically appraised articles published between January 1990 and December 2019 using the Effective Public Health Practice Project Quality Assessment tool. This systematic review provides a synthesis of the available evidence for childhood immunization interventions deemed effective for low SES parents or families of children ≤ 5 years of age.

Synthesis: The search yielded 3317 records, of which 2975 studies met the inclusion criteria. From the 100 relevant studies, a total of 40 were included. The majority of effective and strongly rated studies synthesized consisted of multi-component interventions. Such interventions addressed access, community-based mobilization, outreach, appointment reminders, education, clinical tracking and incentives, and were language and health literacy appropriate to support low SES parents. Improving access to low SES parents was deemed effective in the vast majority of strongly rated studies. Incorrect contact information of low SES parents due to increased social mobility (i.e. household moves) rendered reminders ineffective, and therefore, updating contact information should be pursued proactively by front-line healthcare providers. In addition, plain language communication with low SES parents regarding immunization was deemed effective in improving immunization uptake.

Conclusion: Comprehensive multi-component interventions including improved access, appointment reminders, education and precision health communication are effective for addressing health inequities in immunization coverage amongst marginalized populations. Most low SES parents still believe that the benefits of immunization outweigh the risks.