Perspectives for BCG standardization
Lévy, F.M.; Mande, R.; Conge, G.; Fillastre, C.; Orssaud, E.
Bibliotheca Tuberculosea 24: 63-190
1968
ISSN/ISBN: 0300-1121 PMID: 4984263 Document Number: 3159
There are many difficulties involving the practical application of BCG which are still to be solved. The part which vaccination plays in the control of tuberculosis is important, but needs to be more accurately defined in relation to the epidemiological situation of each country, and it is also necessary to conduct further investigations into the question of revaccination and the comparison of results obtained by various methods. In the same way, attempts recently undertaken to achieve direct vaccination must be continued. These problems cannot be tackled profitably without first endeavouring to standardize the vaccines used, although this necessity was not clearly realized until after the separate vaccination campaigns undertaken by the Scandinavian Red Cross, the United Children's Fund and the World Health Organization, when the striking disparity in their results became apparent. One of the causes for this disparity was probably unequal activity of the vaccines produced by the same laboratory. The necessity of checking the vaccines very carefully is now obvious. Since this fact was recognized many activity tests have been described and put into practice, clinically as well as in the laboratory. The first tests used to determine the value of the vaccines were the allergy tests carried out in man; later it was discovered that the enumeration of colonies made in the laboratory was of importance, and further in vitro techniques were suggested. Lastly, the verification of the activity of vaccines in animals became increasingly widespread and was greatly influenced by the methods of other fundamental studies. For many years, research workers confined themselves to normalization trials, carried out separately in several preparation centres. However, the question remained whether it was possible, in addition, to test the activity of a whole group of vaccines with some precision by using jointly the results obtained from the observation of vaccinates as well as those obtained from the laboratory tests. About fifteen years ago the Pilot Station and the Laboratories of the International Children's Centre tackled this problem, under the direction of DEBRA and Dims. The techniques of production and the so-called safety tests for harmlessness were not performed. Initially the vaccines—mainly dry vaccines for intradermal injection — were kindly supplied by the preparation laboratories themselves. Later (from 1957 onwards) joint investigations were organized by the World Health Organization and the International Union Against Tuberculosis, in which investigations the International Children's Centre has been happy to participate. A comprehensive description of the techniques used was published in 1955; this was subsequently slightly altered and expanded. In this paper, we shall confine ourselves to a broad outline of these techniques. Owing to the circumstances in which they were used, two samples of BCG differing in only one factor were often tested on the same day and under identical conditions. Thus the influence of the age of the culture and that of lyophilization are relatively easy to study. In other circumstances, two types of vaccine differing in various characteristics were compared in a single study. The analysis of the factors which may cause discrepancies is thus rendered difficult, so that the part played by the origin of the substrain, revealed mainly on laboratory cultures, is not always easy to define with the vaccines used in clinical work. However, it is very conspicuous. Finally, an attempt was made, by using the same methods throughout, to make the series of tests carried out from 1955 to 1960 into a coherent whole, and it is therefore possible, with the assistance of these results, to throw some light on the relations between the various tests and to define the part played by each test in the control of vaccine activity.
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