He started his career in a diagnostic virology context but expanded his research interest to viral evolution and ecology after he co-discovered the SARS-coronavirus. He has since worked on the ecology of RNA viruses in mammals and insects, while maintaining a focus on epidemiological and molecular virology of emerging coronaviruses. He has co-authored more than 280 peer-reviewed papers. He currently heads the Institute of Virology at Charité – Universitätsmedizin Berlin.