Preexisting Heterotypic Ligand-blocking Antibody Does Not Protect Against Genogroup II Norovirus Episodes in Young Children

Almost one-half of young children who experienced a norovirus GII episode had preexisting ligand-blocking antibodies to other GII genotypes tested (GII.4, GII.12, or GII.17). Our findings show that these heterotypic antibodies did not provide cross-protection within the GII genogroup. A birth cohort design was used to understand whether heterotypic ligand-blocking norovirus antibodies provide cross-protection within the GII genogroup. We found that almost one-half of children who experienced a norovirus GII episode had preexisting antibodies heterotypic to the infecting genotype; therefore, these antibodies did not provide cross-protection.