During this Conference we have learned that most of the important problems connected with immunization against measles have been solved. Undoubtedly there are problems which now lie beyond our level of perception. It is to be hoped that diligent efforts to apply the total body of knowledge of virology to measles immunization will avoid or minimize these presently unforeseen problems. I shall mention a few of the recognizable problems that will continue to require study for a time.
Although the vaccine disease induced in healthy children by attenuated measles virus is now well understood, more experience is needed in the immunization of children who have nutritional deficiencies, particularly those in the developing areas of the world. Among members of the latter group, will it be essential to control the infection caused by living vaccine by first eliciting partial resistance with γ-globulin or killed vaccine?
Another problem is concerned with the