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Effectiveness of oral killed typhoid vaccine
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This study evaluated an oral killed typhoid vaccine in Delhi children. The vaccine, containing killed Salmonella typhi, did not significantly reduce typhoid fever incidence compared to placebo.
Area of Science:
- Epidemiology
- Vaccinology
- Infectious Diseases
Background:
- Typhoid fever remains a significant public health concern, particularly in developing regions.
- Effective vaccination strategies are crucial for controlling typhoid outbreaks.
- Oral typhoid vaccines offer a potential alternative to injectable formulations.
Purpose of the Study:
- To assess the efficacy of an oral killed typhoid vaccine in preventing typhoid fever.
- To compare the incidence of bacteriologically confirmed typhoid fever in vaccinated versus placebo groups.
Main Methods:
- A controlled field trial involving 13,374 children under 17 years in Delhi, India (1968-1969).
- Participants received either three tablets of oral killed Salmonella typhi vaccine or placebo.
- Follow-up occurred from June 1968 to August 1969, with effectiveness measured by typhoid fever incidence.
Main Results:
- No statistically significant difference in typhoid fever incidence was observed between the vaccinated and placebo groups.
- The study focused on bacteriologically confirmed cases of typhoid fever for accurate assessment.
Conclusions:
- The oral killed typhoid vaccine, administered at the tested dosage, demonstrated no significant effectiveness in preventing typhoid fever.
- Further research may be needed to explore alternative oral typhoid vaccine formulations or dosages.
Abstract:
A controlled field trial of oral killed typhoid vaccine was carried out in Delhi, India in 1968-69. Altogether, 13 374 children below the age of 17 years were included in the study. Two comparable groups of children were given either placebo or vaccine. Each tablet of vaccine contained 100x10(9) killed Salmonella typhi, and 3 tablets of vaccine or placebo were administered to each child. The vaccinated subjects were followed up from 10 June 1968 to 31 August 1969. The effectiveness of the vaccine was measured by comparing the incidence of typhoid fever (based only on bacteriologically positive cases) in the two groups. It was found that the difference in incidence of the disease in the two groups was not statistically significant. The oral killed typhoid vaccine in the dosage schedule used in the present trial was found not to be effective against the disease.