Nicola Klein, MD, PhD is a board-certified Pediatrician, Director of the Kaiser Permanente Vaccine Study Center, Research Scientist III at the Kaiser Permanente Northern California Division of Research, and a Professor in the Department of Health Systems Science at the Kaiser Permanente Bernard J. Tyson School of Medicine. Her research has focused on vaccine safety and effectiveness in all populations and on the epidemiology of vaccine preventable diseases. She had led pivotal studies describing waning effectiveness of acellular pertussis vaccines and the effectiveness of maternal Tdap in protecting infants against pertussis. She has also led extremely large pragmatic, randomized studies comparing the effectiveness of different influenza vaccines, as well as observational studies investigating many other vaccines, including live-attenuated zoster, influenza, human papilloma virus, pneumococcal conjugate vaccines, COVID-19, recombinant shingles vaccines. She is the principal investigator (PI) for the CDC-sponsored networks, including the Vaccine Safety Datalink (VSD) Project, the Clinical Immunization Safety Assessment Network and the Virtual SARS-CoV-2, Influenza, and Other respiratory viruses (VISION) VE Network. During the pandemic, she led the VSD COVID-19 vaccines Rapid Cycle Analysis, which monitors the safety of vaccines in near real-time and was the CDC’s primary active surveillance safety monitoring system for COVID-19 vaccines. She is PI for both industry and federally sponsored Phase 2 and 3 vaccine clinical trials. She served on the Western States Scientific Safety Review Workgroup for COVID-19 vaccines, National Vaccine Advisory Committee (NVAC) Vaccine Safety Subcommittee, National Academy of Science, Engineering and Medicine (NASEM) Board on Population Health and the World Health Organization (WHO) Pertussis Technical Consultant Panel/pre-SAGE Working Group. She is currently a member of the Brighton Collaboration Science Board, the NASEM Health Care and Public Health Program Advisory Committee and the WHO Strategic Advisory Group of Experts (SAGE) Pertussis Working Group.