Zimmerly studied law and medicine while serving in the United States Army. He obtained his Doctor of Medicine from the University of Maryland School of Medicine in 1966 and studied law at the while working as an intern at Walter Reed General Hospital, graduating in 1969. He also completed a Master in Public Health at Johns Hopkins University in 1969.
He co–discovered a vaccine for meningitis in 1970. He died in 2002 following a brain aneurysm and is buried in Arlington National Cemetery. While serving two tours in Vietnam and Cambodia, Zimmerly tracked infectious diseases including malaria, hepatitis and tuberculosis with the aim of protecting troops.
He retired with the rank of colonel.
Zimmerly co-discovered the vaccine for meningitis while completing his residency at Walter Green Hospital in Baltimore. After the initial animal studies for the vaccine failed, he tested it on himself, before going on to conduct a full study on 13,763 army recruits.
He became the chief of legal medicine for the Armed Forces Institute of Pathology in 1971 and served as chair until 1991. After he retired from the Army he served as chair and president at the Baltimore Rh Typing Laboratory as well as working for Monumental Life Insurance as a medical director
