Dr. Grabenstein is a global vaccinologist, pharmacist, epidemiologist, and public-health leader specializing in adult vaccines, implementation, and vaccine history. Currently, Dr. Grabenstein is president of consulting service Vaccine Dynamics SP, and is also Associate Director of Scientific Communications for the Immunization Action Coalition (IAC), a non-profit organization working to increase immunization rates and prevent disease by creating and distributing educational materials for health professionals and the public. Previously, he spent over 13 years at Merck Vaccines, most recently serving as Global Executive Director of Medical Affairs until his retirement in late 2019. Before joining Merck, Dr. Grabenstein served for 27 years in the U.S. Army Medical Department, achieving the rank of Colonel. From 1999 to 2006, he directed the scientific elements of the U.S. Department of Defense (DoD) anthrax and smallpox vaccination programs. As Director, Military Vaccine Agency, he was responsible for science, communication, education, and safety surveillance of military immunizations for 2.6 million U.S. Army, Navy, Marine Corps, Air Force, and Coast Guard personnel deployed globally.