Salmonella Paratyphi A vaccine

**Salmonella Paratyphi A vaccine** refers to investigational vaccines targeting *Salmonella enterica* serovar Paratyphi A, the primary cause of paratyphoid fever, a form of enteric fever affecting over 2 million people annually, mainly in Asia and Africa via contaminated food and water. The leading candidate, **CVD 1902**, is a live-attenuated oral vaccine developed at the University of Maryland, expressing key antigens like O lipopolysaccharide and FliC flagellin to induce humoral (IgG/IgA) and cellular (CD4+/CD8+ T-cell) immunity mimicking natural infection while attenuating virulence. In a phase 2b human challenge trial, two oral doses demonstrated **73% vaccine efficacy** against controlled *S. Paratyphi A* exposure, with a favorable safety profile (mild GI events like nausea predominant). No licensed vaccine exists; CVD 1902 is licensed to Bharat Biotech for potential bivalent development with *S. Typhi* vaccines to comprehensively prevent enteric fever.