title: Is there a synergistic effect between previous and current vaccination against influenza?
mesh_terms: D004357:Drug Synergism; D006801:Humans; D007117:Immunization, Secondary; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000401:mortality / Q000517:prevention & control*
chemical_list: D007252:Influenza Vaccines