Immunization against measles with inactivated vaccine

Abstract

The theoretical and practical considerations in the use of attenuated measles virus vaccine for immunization against measles are familiar to all, and have been discussed in detail at this meeting. In this brief discussion I will attempt to clarify some aspects of the use of inactivated measles vaccine for the prevention of measles.The premise for the successful use of inactivated measles vaccine is composed of several integral parts. The vaccine should provide protection against measles without causing significant or serious side-effects. Since protection is usually associated with the development of an antibody response, the vaccine should stimulate this response in a high percentage of individuals. Also of importance is the requirement that the antigen should be of sufficient potency to produce a state of immunologic hyperreactivity in the subject, so that at a later date upon natural exposure, the immune mechanism will respond quickly enough to eliminate completely or markedly alter the symptoms of the disease, while still allowing the subclinical infection to take place. If the state of immunologic hyperreactivity persists, and if a reservoir of wild virus for natural challenge persists, it should not be necessary to give booster doses of inactivated measles vaccine at a later date.Since the antibody titer of an individual is only a reflection of the degree of activity of his antibody mechanism, a decline in antibody may not represent an absolute loss of immunity. It is necessary not only to evaluate the level of antibody in the individual, but also to study the natural clinical history of the subject over a prolonged period of time in order to determine the ultimate immune response to challenge by the "wild" virus. Our efforts, therefore, have been directed toward evaluation of inactivated measles vaccine of various potency levels, not only from the point of view of antibody response, but also by studying the several vaccines under conditions of normal clinical use. The vaccines were pro-

Response of Children to Inactivated Measles Vaccine Prepared in Bovine Renal Cell Culture

“…The vaccines employed in these previous studies were prepared from virus grown in either monkey kidney or chick embryo cell cultures [18,19,35,40]. Direct comparison of the antibody response of the children in our study to those of previous studies is difficult, but it is evident that the vaccine tested in the present study had as good a potency in children as currently used killed vaccines.…”

“…It has been repeatedly confirmed that inactivated measles vaccines of suitable potency give a high rate of serologic conversions and protection from natural measles [5, 7, 8-16, 18, 19, 22-26, 35-37, 40-42, 44, 46-48]. The vaccines employed in these previous studies were prepared from virus grown in either monkey kidney or chick embryo cell cultures [18,19,35,40]. Direct comparison of the antibody response of the children in our study to those of previous studies is difficult, but it is evident that the vaccine tested in the present study had as good a potency in children as currently used killed vaccines.…”