Dr. Johannes Nießen, M.D., is a German physician and a well-known expert in public health, with specialist qualifications in general medicine, public health, and social medicine. He has held leading positions in the German public health service for more than two decades, including as Director of the Hamburg-Altona Public Health Department from 2002 to 2019 and subsequently as Director of the Cologne Public Health Department until 2023. Since October 2023, he has served as the founding director and as Acting Director of the Federal Institute for Public Health (BIÖG).

Dr. Nießen has also contributed his expertise to public health policy at the national level. In 2021, he was a member of the expert council commissioned by the Federal Chancellery to advise the German federal government on the COVID-19 pandemic. From 2022 to 2023, he served as Chairman and Executive Director of the Federal Association of Physicians in the Public Health Service (BVÖGD).