The Big Catch-up is a global initiative to close immunization gaps caused by the backsliding of immunization coverage during the COVID-19 pandemic, restore global immunization levels, and strengthen immunization systems so that catch-up activities become an integral part of immunization programmes. This page brings together Big Catch-up documents including guidance, frequently asked questions (FAQs), and monitoring, evaluation, and learning (MEL) forms and tools, as well as a forum for sharing country experiences, updates, and materials.