title: Leads from the MMWR. Antigenic analysis of recent influenza A (H1N1) viruses.
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000032:analysis*; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus / Q000276:immunology*
chemical_list: D000956:Antigens, Viral