Safety and immunogenicity of Shigella sonnei and Shigella flexneri 2a O-specific polysaccharide conjugates in children

O-specific polysaccharide conjugates of shigellae were safe and immunogenic in young adults, and a Shigella sonnei conjugate conferred protection [1-3 ], Shigellosis is primarily a disease of children; therefore, the safety an d immunogenicity of S. sonnei and Shigella flexneri 2a conjugates were stud ied in 4- to 7-year-old children. Local and systemic reactions were minimal . The first injection of both conjugates elicited significant rises in geom etric mean levels of serum IgG only to the homologous lipopolysaccharide (L PS) (S, sonnei, 0.32-8.25 ELISA units [EU]; S. flexneri 2a, 1.15-20.5 EU; P < .0001), Revaccination at 6 weeks induced a booster response to S. flexne ri 2a LPS (20.5-30.5 EU, P = .003). Six months later, the geometric mean le vels of Ige anti-LPS for both groups were higher than the prevaccination le vels (P < .0001). Similar, but lesser, rises were observed for IgM and IgA anti-LPS, The investigational Shigella conjugates were safe and immunogenic in children and merit evaluation of their efficacy.