Experimental Vaccination Against Measles: Clinical Evaluation of a Highly Attenuated Live Measles Vaccine

ISOLATION of measles virus in tissue culture and its adaptation to growth in embryonated eggs and chick embryo-cell culture resulted in development of vaccines suitable for use in prophylaxis of measles. 1 Three types of measles vaccines are being studied at present: vaccine containing killed virus; 2-6 live attenuated virus (Enders strain); 7-8 and a live virus strain (Schwarz strain), which has been further attenuated than the Enders strain. 9 Severe reactions to the killed virus vaccines have not been reported, but several injections of a concentrated virus vaccine are necessary to produce significant antibody levels. While the duration of protection has not been determined, it appears to be maintained for only a relatively short time in some cases. 3 Live measles vaccines of the Enders strain, on the other hand, produced excellent immunity after one injection but caused undesirable reactions consisting of moderate to high fever and modified measles