A Bivalent Human Norovirus Vaccine Induces Homotypic and Heterotypic Neutralizing Antibodies.

A GII.2 outbreak in an efficacy study of a bivalent virus-like particle (VLP) norovirus vaccine, TAK-214, in healthy US adults provided an opportunity to examine GII.4 homotypic vs. GII.2 heterotypic responses to vaccination and infection. Three serological assays (VLP-binding, histoblood group antigen-blocking, and neutralizing) were performed for each genotype. Results were highly correlated within a genotype but not between genotypes. Although the vaccine provided protection from GII.2-associated disease, little GII.2-specific neutralization occurred after vaccination. Choice of antibody assay can affect assessments of human norovirus vaccine immunogenicity.