Cross-reactive gut-directed immune response against Salmonella enterica serovar Paratyphi A and B in typhoid fever and after oral Ty21a typhoid vaccination

► There are no vaccines against Salmonella Paratyphi in clinical use. ► Some studies show efficacy with Ty21a-vaccine against paratyphoid A/B fever. ► Ty21a elicited gut-directed plasmablasts cross-reactive with Salmonella Paratyphi. ► Plasmablasts reactive with Salmonella Paratyphi were also seen in typhoid fever. ► The data reveal a cross-reactive potential of Ty21a against paratyphoid fever.