typhoid + paratyphoid A conjugate vaccine

A **typhoid + paratyphoid A conjugate vaccine** is a bivalent vaccine designed to provide immunity against both *Salmonella enterica* serovar Typhi (**typhoid fever**) and *Salmonella enterica* serovar Paratyphi A (**paratyphoid fever**)[2][3][7]. This vaccine typically consists of the **Vi capsular polysaccharide antigen** from *S. Typhi*, conjugated to a carrier protein (such as tetanus toxoid, diphtheria toxoid, or recombinant proteins), together with an **O:2 polysaccharide antigen** from *S. Paratyphi A* similarly conjugated to a suitable carrier protein[2][3][7]. The mechanism of action involves induction of humoral immunity (production of high-titer IgG antibodies) as well as cell-mediated immune responses (activation of Th1 and cytotoxic T-lymphocytes) against both the Vi antigen and O:2 antigen, conferring protection against the respective pathogens[2][3]. Bivalent conjugate vaccines are in late clinical development, with trials in infants and older age groups demonstrating safety and immunogenicity[3][7].

Other names

bivalent typhoid-paratyphoid A conjugate vaccinebivalent typhoid-paratyphoid vaccine