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Immunogenicity of Salmonella typhi Ty21a vaccine for young children
J R Murphy1, L Grez, L Schlesinger
1Department of Medicine, University of Maryland School of Medicine, Baltimore 21201.
Insights
The Salmonella typhi Ty21a vaccine was safe but not immunogenic in infants and toddlers under 24 months. This suggests the vaccine
Area of Science:
- Pediatric Vaccinology
- Microbial Immunology
Background:
- Typhoid fever remains a significant global health concern.
- The live attenuated Salmonella typhi Ty21a vaccine is used in older children and adults.
Purpose of the Study:
- To evaluate the safety and immunogenicity of the Salmonella typhi Ty21a vaccine in infants and toddlers (≤24 months).
Main Methods:
- 18 infants and toddlers received three doses of Ty21a vaccine (10^9 CFU/dose).
- Safety was monitored through tolerability assessments.
- Humoral and cellular immune responses to S. typhi were assessed post-vaccination.
Main Results:
- The Ty21a vaccination was well tolerated in the study population.
- No evidence of humoral or cellular immune response to S. typhi was detected after vaccination.
- The vaccine is known to be immunogenic in older age groups.
Conclusions:
- The immunogenicity of the Salmonella typhi Ty21a vaccine appears to be age-dependent.
- Ty21a vaccine may not be effective in inducing an immune response in infants and toddlers.
Abstract:
An attenuated Salmonella typhi Ty21a vaccine was administered to 18 infants and toddlers (less than or equal to 24 months old) to determine its safety and immunogenicity. The vaccination (10(9) CFU per dose, three doses) was well tolerated. However, after the vaccination there was no evidence of a humoral or cellular immune response to S. typhi. The vaccine used was known to be immunogenic for older children and adults. The results support the view that the immunogenicity of Ty21a is age dependent.