John F. Enders and measles virus vaccine--a reminiscence.

Following their initial isolation in cell culture of the virus in 1954, a succession of investigators under the mentorship of John E Enders conducted the research, development, and initial clinical studies responsible for the licensure in 1963 of a successful live attenuated measles virus vaccine. Propagation of the virus successively in human kidney cells, human amnion cells, embryonated hens' eggs, and finally chick embryo cell cultures had selected virus that when inoculated into susceptible monkeys proved immunogenic without viremia or overt disease, in contrast to the early kidney cell-passaged material, which in similar monkeys produced viremia with illness mimicking human measles. Careful clinical studies in children by the Enders group and then by collaborating investigators in many sites established its safety, immunogenicity, and efficacy. This Edmonston strain measles virus became the progenitor of vaccines prepared, studied, and utilized throughout the United States and many other countries. With appreciation of measles morbidity and mortality, most marked among infants and children in the resource-limited lands, the vaccine was incorporated into the World Health Organization's (WHO) Expanded Programme of Immunization (EPI) in 1974 along with BCG, OPV, and DTP. Successful efforts to further reduce measles' burden were launched in 2001 and are continuing as the Measles Initiative (Partnership) under the leadership of the American Red Cross, International Red Cross, and Red Crescent societies, Centers for Disease Control (CDC), United Nations Children's Fund (UNICEF), WHO, and the United Nations Foundation.