A Phase I, dose-escalation trial in adults of three recombinant attenuated Salmonella Typhi vaccine vectors producing Streptococcus pneumoniae surface protein antigen PspA

All three S. Typhi vectored pneumococcal vaccines were safe and well-tolerated. Immunogenicity was limited possibly due to pre-existing high antibody titers prior to vaccination. Increases in IgA were most often observed.