The Schick test and active immunisation / R.A. O'Brien [and others].

Date:
[1923?]
Catalogue details

Licence: In copyright

Credit: The Schick test and active immunisation / R.A. O'Brien [and others]. Source: Wellcome Collection.

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    B weeks 129, i.e. 94 per cent., showed a negative Schick reaction; thereafter the results were as follows, the figures in brackets giving the number yielding a Schick-negative reaction at the expiry of the corresponding number of weeks: 9 (2), 10 (1), 11 (1), 21 (2). One child, though reinjected, remained positive; we hope to be able to re-examine him later. With regard to the permanence of the negative reaction in immunised children, we had the opportunity of re-testing a group of 203 children, both those originally negative to the Schick test, and also those who had become negative after immunisation. When re-tested 11 weeks, later the reactions agreed in 201 cases; 2 who had been negative now gave a positive reaction. Inquiry revealed that these children had had antitoxin injected some few weeks before the first test was carried out. To one question of interest we have only a partial answer. From our general knowledge of immunity it is to be expected that a school population showing a high percentage of Schick-negative reactors and having a recent hi story ^of diphtheria would be one easily immunised. This anticipation is realised in the large groups of figures given by Zingher. We know also from Dudley’s careful work (1922) that a population of boys exposed to an epidemic of diphtheria will show a high percentage of “ Schick-negative reactors.” It would be of great scientific interest to know how many of the children would have become immune without the injection. Probably some few of them would. We have had unfortunately, in this, as in so many other aspects of this work, very restricted opportunities of making observations under satis¬ factory conditions; however, at one school, 19 children who gave Schick¬ positive reactions did not become available to us again for seven months, during which time the remainder of the positive reactors in the school were immunised. All of these 19 children were now injected. Five weeks after the completion of the course of injection these children were again tested ; 5 of them gave a positive response. Thus, this group of 19 children who had been in contact with the other children and had also recently had prophy¬ lactic injections showed an immunity rate of only 74 per cent., whereas the children who had been fully immunised at this time gave a 99 per cent, immunity rate. Though the figures are small, they indicate that the increased immunity rate in the whole school was almost entirely the result of the toxin- antitoxin injections. The figures from the welfare centre may be of further help. Of these children only 24 per cent, were Schick-negative reactors when they were first examined. Of 33 children tested, found positive and injected with mixtures, 31 {m6m 93 per cent, became Schick-negative reactors within 12 weeks. During this period no cases of diphtheria were notified within the area. Small ^groups of fresh children were still being tested each week, and the immunity rate was still between 25 and 30 per cent. It is reasonable to conclude that in this particular-population, the greater part of the conversion of the “ Schick-positive ” population to a “ Schick¬ negative ” one was due to the injections given. Reactions after injection of toxin-antitoxin mixture.—The reactions in these groups of children have been wery slight: with the exception of three instances in our early work we have no record that any child developed a