Duration of Vi antibodies in participants vaccinated with Typhim Vi (Typhoid Vi polysaccharide vaccine) in an area not endemic for typhoid fever.

After a single injection of Typhim Vi (typhoid Vi polysaccharide vaccine), serum antibody concentrations were monitored for 3 years in 37 adults who resided where typhoid fever was not endemic. Anti-Vi antibody concentrations declined progressively during the study, to levels that support the current US recommendation for revaccination every 2 years.