Efficacy of one or two doses of Ty21a Salmonella typhi vaccine in enteric-coated capsules in a controlled field trial. Chilean Typhoid Committee.
Vaccine
; 8(1): 81-4, 1990 Feb.
Article
en En
| MEDLINE
| ID: mdl-2180234
Typhoid fever remains an important public health problem in many areas of the world and an effective, non-reactogenic vaccine would be useful to control this disease. An attenuated Salmonella typhi strain (Ty21a), which has shown promise in previous trials, was evaluated in a controlled field trial in Santiago, Chile. In this trial, 82,543 schoolchildren were randomly assigned to receive one or two doses of Ty21a vaccine in enteric-coated capsules or placebo. The enteric-coated vaccine formulation was well tolerated and practical for mass oral immunization. In the first two years of surveillance, 213 cases of bacteriologically-confirmed typhoid fever were found in schoolchildren participating in the trial; annual rates in the placebo group were 139 and 227 per 100,000. Vaccine efficacy in the first two years after vaccination was 59% for two doses and 29% for one dose; no efficacy was found 3-5 years after vaccination. These results indicate that it will be necessary to identify a vaccine formulation and schedule for Ty21a S. typhi that is practical and provides high level protection for greater than 2 years.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Salmonella typhi
/
Fiebre Tifoidea
/
Vacunas Tifoides-Paratifoides
Tipo de estudio:
Clinical_trials
Límite:
Adolescent
/
Adult
/
Child
/
Humans
País/Región como asunto:
America do sul
/
Chile
Idioma:
En
Revista:
Vaccine
Año:
1990
Tipo del documento:
Article
Pais de publicación:
Países Bajos