"The Immunization Data: Evidence for Action (IDEA) Review: A Realist Review of What Works to Improve Data Use for Immunization Evidence from low- and middle-income countries", is a global synthesis of existing evidence aimed at increasing the use of high-quality data to improve immunization coverage. The IDEA review draws on nearly 550 documents including published literature, working papers, project evaluations and reports, which were distilled and prioritized by global immunization experts. The review, published in 2019 and made available in English, French and Spanish (see Report website here), was funded by the Bill & Melinda Gates Foundation and developed in partnership between PATH and the Pan American Health Organization (PAHO).