title: Antigenic variation of recent influenza A(H1N1) viruses.
mesh_terms: D000328:Adult; D000956:Antigens, Viral / Q000276:immunology*; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D007106:Immune Sera; D007252:Influenza Vaccines