An evaluation of diphtheria immunization

Abstract

Summary 1. Three injections of toxin-antitoxin mixture given in 1 c.c. doses at weekly intervals renders immune at the end of six months about 70 per cent of children and less than this of adults. Four doses of 1 c.c. each given at weekly intervals probably immunizes about 80 to 90 per cent of children. Five doses of 1 c.c. each at weekly intervals immunizes about 85 per cent of adults. 2. Toxin-antitoxin properly underneutralized and stored gives practically no local or general reactions. 3. Toxin-antitoxin mixture is capable of sensitizing individuals to horse serum. 4. The substitution of sheep or goat serum for horse serum in the preparation of toxin-antitoxin mixture has been done. The percentage immunization with this is about the same as with the horse serum toxin-antitoxin. 5. One series of toxin-antitoxin injections does not endanger the individual to later injections of toxin-antitoxin inasmuch as the total amount of horse serum in 1 c.c. of mixture is not sufficient to produce shock even if hypersensitive to horse serum. 6. Immunization with toxoid by any method of 2 or more injections of 1 c.c. each produces 90 to 100 per cent immunity in three to six months. 7. Reactions in older children and adults are the chief objections to the use of toxoid as an immunizing agent. 8. Duration of immunity whether naturally or artificially produced is good. It is apparently more lasting if immunization is done in childhood than in adult life. There is some evidence that the individuals more resistant to immunization revert to the Schick positive state more readily. 9. The Schick test, properly carried out, is a reliable indication of immunity to diphtheria and should be considered part of the immunization procedure. 10. Individuals Schick positive in spite of the routine immunization procedure can and have contracted diphtheria. 11. A standardization of methods of immunization is desirable. 12. The ideals still to be reached are (a) an agent that gives no reactions in any age group; (b) an agent that immunizes close to 100 per cent; (c) a simpler method less subject to error for testing for immunity.