ABSTRACT
Vaccines against COVID-19 have been available in Germany since December 2020. At the Robert Koch Institute (RKI), the Immunization Unit is responsible for monitoring vaccination coverage and assessment of vaccine effectiveness. This article provides an overview of the respective reporting structures, vaccination databases, and epidemiological studies established by the Immunization Unit during the COVID-19 pandemic. We describe the COVID-19 Digital Vaccination Coverage Monitoring (DIM), which provides daily updates on vaccination coverage by age group. We next describe how, based on the DIM data and COVID-19 case data, the assessment of vaccine effectiveness against different clinical endpoints (hospitalization, intensive care, death) is performed. While this method is used for a preliminary estimate of vaccine efficacy, population-based nonrandomized studies are able to provide more precise and detailed estimates under "real-world" conditions. In this context, we describe the hospital-based case-control study COViK, which is being conducted in collaboration with the Paul Ehrlich Institute (PEI). We discuss strengths and limitations of the abovementioned structures and tools. Finally, we provide an outlook on future challenges that may arise during the ongoing pandemic and during the transition phase into an endemic situation.