In a vaccination and laboratory study, two dried smallpox vaccines (designated P and Q) were tested at intervals of 4, 8, 16, and 32 weeks after storage at both 37 degrees C and 45 degrees C. Vaccine P was also tested after 64 weeks at these temperatures and gave 100% successful vaccination rates after all periods of storage at both temperatures. Vaccine Q deteriorated within four weeks, rapidly at 45 degrees C and less rapidly, but very substantially, at 37 degrees C. There was no clear evidence of the cause of this deterioration, but there was a suggestion of denaturation of some of the samples stored at the higher temperature. So far as could be ascertained, the laboratory results-rabbit skin scarification tests and chorio-allantoic membrane pock counts-ran parallel with the vaccination success rates. The pock count was found to be the more accurate method of laboratory titration. Vaccine P as used in the trial was not an exceptional batch.Vaccines which give a pock count of 10(8) infective units per ml will give the highest possible rate of successful primary vaccinations.A statistical note on the trials is given in an annex.

Animals↗

PubMed1955

The early history of typhoid vaccination.

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Allergy and Immunology↗

PubMed1955

Large-scale field trials of active immunizing agents; with special reference to vaccination against pertussis.

In this discussion of the methods to be used in large-scale field trials of active immunizing agents and of the results to be expected from such trials, special emphasis is laid on pertussis vaccine trials in Great Britain. After a review of the criteria for strictly controlled field studies and of the investigation of typhoid vaccines conducted in 1904-08 by the Antityphoid Committee of the British Army, the author describes the pertussis vaccine studies which have been and are now being carried by the Whooping-Cough Immunization Committee of the Medical Research Council of Great Britain.The original strictly controlled trials have been completed and the results published. Studies are now being made of vaccines prepared by different methods and evaluated both in the field and in the laboratory. Each vaccine is given to some 2000-3000 children of 4-6 months to 4 years of age. By the end of the studies 30 000-40 000 children will have been followed up for a period of two years. Since in the current studies all the children are vaccinated and none are left as unvaccinated controls, the relative and not the absolute protective value of the vaccines will be measured.

Child↗

PubMed1955

The use of mixed diphtheria-pertussis-tetanus antigens.

The author reviews the use of mixed diphtheria-pertussis-tetanus antigens in the light of the information which has become available in recent years. When diphtheria toxoid and tetanus toxoid, adsorbed or unadsorbed, are added to either plain or adsorbed pertussis vaccine, a satisfactory level of diphtheria antitoxin can be obtained in children over 6 months of age and of tetanus antitoxin in children of any age. As to the duration of immunity, it appears that provided three doses of mixed antigens are given for the primary immunization of children 6 months old a substantial proportion will have effective antitoxin titres three years later, but that with two doses only the antitoxin levels fall more rapidly.Reviewing the evidence, the author considers that mixed antigens will be useful in future immunization campaigns, although he makes it clear that extensive investigations, particularly on the immunizing effect of the pertussis component, must be undertaken before their value can be finally assessed.The reactions to and complications after inoculation with mixed antigens are then discussed, particularly in relation to convulsions, encephalopathy, and poliomyelitis. Finally, the author considers provisional recommendations for the use of mixed antigens, pointing out that the main question in all countries is whether the advantages of giving all three antigens simultaneously to children under 6 month of age, necessary because of the pertussis mortality in the first months of life, outweigh the disadvantages.

Child↗

PubMed1954