Bivalent conjugate vaccines for typhoid and paratyphoid fever

Enteric fever is caused by Salmonella enterica serovars Typhi and paratyphi serovars Paratyphi A, Paratyphi B, and Paratyphi C that can cause severe and sometimes life-threatening systemic bacterial infection in humans. Clinical features are indistinguishable between the two serovars and humans are the only known reservoir. Risk for infection is high in low-income and lower-middle-income countries, particularly in south and southeast Asia in settings where there is scarce access to safe water and poor sanitation systems.