title: [Pre-existing immunity is an essential factor for mild pandemic H1N1 2009].
authors.affiliation: dayanwang@cnic.org.cn
authors.forename: Da-Yan
authors.initials: DY
authors.lastname: Wang
authors.forename: Yue-Long
authors.initials: YL
authors.lastname: Shu
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000235:genetics; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology; D058873:Pandemics; D013997:Time Factors
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; C483468:hemagglutinin, human influenza A virus