Immunogenicity of Salmonella typhi Ty21a vaccine for young children

Abstract

An attenuated Salmonella typhi Ty21a vaccine was administered to 18 infants and toddlers (≤24 months old) to determine its safety and immunogenicity. The vaccination (109 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.