Dr. Gessner is currently Vice President and Global Medical Lead for Pneumococcal Vaccines at Pfizer Vaccines, a position he has held since December 2016. He also maintains an affiliation as an adjunct professor at the University of Maryland and serves on the Board of Agence de Medicine Preventive (AMP). Before joining Pfizer, he served as the Scientific Director and Chief Scientific Officer at AMP for 20 years, and started and developed the Maternal and Child Health Epidemiology Unit at the Alaska Division of Public Health. Dr. Gessner completed pediatric and preventive medicine residencies, an MPH, and a CDC Epidemic Intelligence Service fellowship. He has authored over 220 peer-reviewed manuscripts primarily on vaccines and vaccine preventable diseases from studies conducted in 30 different countries. He has served on WHO's IVIR-AC and IPAC expert committees, several SAGE working groups, and on the Gavi Board.