Frenck RW, et al. - Safety, reactogenicity, and immunogenicity of ExPEC4V, a bioconjugate vaccine, developed to prevent invasive extra-intestinal pathogenic E coli disease, were assessed in healthy adults in this phase 2 randomized, double-blind placebo-controlled study. Researchers randomly assigned healthy adults (≥18 years with a body-mass index of 35 kg/m 2 or less) to receive a single dose of ExPEC4V (antigen O1A:O2:O6A:O25B content 4:4:4:4 μg [group 1]; 4:4:4:8 μg [group 2], 8:8:8:8 μg [group 3], 8:8:8:16 μg [group 4], or 16:16:16:16 μg [group 5]) or placebo. Outcomes suggest that participants were able to tolerate EXPEC4V and the vaccine evoked strong and functional antibody responses across all serotypes, doses, and age groups. Persistence of the immune response for 1 year was noted for the two dosages evaluated.