False Positive Reactions to the Schick Test

It has been known almost since active diphtheria immunization was begun that systemic reactions to diphtheria inoculations were more common among adults than among children. Since 1928 the Moloney test1has made it possible to detect many of these potential reactors. Because there has been little or no adult immunization since the widespread introduction of immunization in childhood, the problem of reactions has never been a serious one. However, with the recently increasing consciousness of the potential danger of a nonimmune adult population,2immunization procedures among young adults may be indicated in suitable circumstances. The results of this study appear to demonstrate that the great majority of severe systemic reactions are avoidable, since they occur in immune persons who needed no immunization. They indicate also that the reaction to the ordinary Schick test, when positive, is not a completely reliable index of susceptibility to diphtheria. METHODS Young pregnant