Dr. Chen has been active in research of vaccines and vaccine-preventable diseases for over 35 years, mostly at the US Centers for Disease Control and Prevention (CDC). He played key roles in modernizing the vaccine safety infrastructure in the U.S. and elsewhere, including the creation of the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD) project, the Clinical Immunization Safety Assessment (CISA) Network, the Brighton Collaboration, the Safety Injection Global Network (SIGN), and Vaccine Special Interest Group (VAXSIG) of the International Society of Pharmacoepidemiology. He has authored or coauthored 280 publications. Dr. Chen is currently the Scientific Director of the Brighton Collaboration.