Tetravalent Recombinant Norovirus vaccine(Zhifei Longcom)

Primary objective: To evaluate the protective efficacy of the quadrivalent recombinant norovirus vaccine against AGE caused by the four genotypes (GI.1, GII.3, GII.4, and GII.17) included in the vaccine. Secondary objectives: (1) To evaluate the protective efficacy of the quadrivalent recombinant norovirus vaccine against AGE caused by all norovirus genotypes; (2) To evaluate the protective efficacy of the quadrivalent recombinant norovirus vaccine against moderate to severe AGE caused by all norovirus genotypes; (3) To evaluate the protective efficacy of the quadrivalent recombinant norovirus vaccine against moderate to severe AGE caused by the four genotypes (GI.1, GII.3, GII.4, and GII.17) included in the vaccine; (4) To evaluate the immunogenicity of the quadrivalent recombinant norovirus vaccine; (5) To evaluate the safety of the quadrivalent recombinant norovirus vaccine. Exploratory objectives: (1) To evaluate the AGE protective efficacy of the quadrivalent recombinant norovirus vaccine against repeated infection (same genotype and repeated infection of different genotypes); (2) To evaluate the AGE protective efficacy of the quadrivalent recombinant norovirus vaccine against cross infection (types other than GI.1, GII.3, GII.4, and GII.17);