[METHODS] Adults randomized to 4 study groups and stratified by age ( 18-64 and 65 years ) received 1 dose of seasonal IIV3 or placebo and 2 doses of 2009-H1N1 vaccine or placebo in one of 4 combinations , i.e. , H1N1 + Placebo/H1N1 + Placebo/IIV3 ( HP/HP/V3 ) , H1N1 + IIV3/H1N1 + Placebo/Placebo ( HV3/HP/P ) , H1N1 + Placebo/H1N1 + IIV3/Placebo ( HP/HV3/P ) , and IIV3 + Placebo/H1N1 + Placebo/H1N1 ( V3P/HP/H ) .