1. A method of eliciting protective immunity against Norovirus in a human comprising administering parenterally to the human no more than a single dose of a vaccine composition, said composition comprising(i) genogroup I Norovirus virus-like particles (VLPs), wherein said genogroup I Norovirus VLPs comprise a capsid protein derived from a genogroup I viral strain, and
(ii) genogroup II Norovirus VLPs, wherein said genogroup II Norovirus VLPs comprise a capsid protein derived from a genogroup II viral strain,
wherein said genogroup I Norovirus VLPs and genogroup II Norovirus VLPs are present in the composition in different amounts, wherein said composition comprises about 15 ?g to 50 ?g of genogroup I Norovirus VLPs and about 50 ?g to 150 ?g of genogroup II Norovirus VLPs,
wherein said composition induces at least a three-fold increase in Norovirus-specific serum antibody titer as compared to the titer in the human prior to administration of the composition.