Immunization is one of the most impactful and cost-effective public health interventions available, averting an estimated 2 to 3 million deaths every year. In addition to offering protection from preventable diseases, immunization also brings children and families into contact with health systems, providing an avenue for the delivery of other basic health services and laying the foundation for primary health care. As such, ensuring universal access to vaccines is a critical entry point for universal health coverage (UHC).