The proposed study is a phase IA/B randomized, double-blind, single-center, clinical trial, in healthy adults (18-49 years old) and ambulatory elderly subjects (aged 65 years and older). Phase IA will evaluate the safety, tolerability and hemagglutination inhibition assay (HAI) antibody response of each of four escalating doses of influenza hemagglutinin (HA) antigen with a fixed dose of a water-in-oil emulsion adjuvant MAS-1 (Mercia Adjuvant System-1), compared with licensed, unadjuvanted, standard dose (SD) of licensed inactivated trivalent influenza virus vaccine (IIV). Phase IB will evaluate the optimal dose of IIV in MAS-1 selected under phase IA (known to be 9µg of HA antigen) for safety, tolerability and HAI antibody response in ambulatory elderly subjects compared to high dose (HD) IIV.