Study to Evaluate the Safety and Immune Response of Two-Doses of Candidate Influenza Vaccine GSK 1557484A in Adults

Inclusion Criteria: * Male and female adults 18 to 64 years of age at time of first vaccination, inclusive. * Good general health as assessed by medical history and physical examination. * Access to a consistent means of telephone contact * Written informed consent obtained from the subject. * Comprehension of the study requirements, expressed availability for the required study period, and ability to attend scheduled visits. * Subjects who the investigator believes that they can and will comply with the requirements of the protocol should be enrolled in the study. Exclusion Criteria: * Presence of significant acute or chronic, uncontrolled medical or psychiatric illness * Presence of evidence of substance abuse or of neurological or psychiatric diagnoses which, although stable, are deemed by the investigator to render the potential subject unable/unlikely to provide accurate safety reports. * Blood pressure abnormalities * Diagnosed with cancer, or treatment for cancer, within 3 years. * Persons with a history of cancer who are disease-free without treatment for 3 years or more are eligible. * Persons with a history of histologically-confirmed basal cell carcinoma of the skin successfully treated with local excision only are excepted and may enroll, but other histologic types of skin cancer are exclusionary. * Women who are disease-free 3 years or more after treatment for breast cancer and receiving long-term prophylactic tamoxifen are excepted and may enroll. * Presence of an oral temperature ≥ 37.8º C, or acute symptoms greater than "mild" severity on the scheduled date of first vaccination. * Any confirmed or suspected immunosuppressive or immunodeficient condition including history of human immunodeficiency virus (HIV) infection. * Receipt of cytotoxic or immunosuppressive drug within 6 months of study enrollment. * Any significant disorder of coagulation or treatment with Coumadin derivatives or heparin. * Administration of any non-influenza vaccines within 30 days before study enrollment or during the study period. * Use of any investigational or non-registered product (drug or vaccine) or planned participation in another investigational study within 30 days prior to study enrollment, or during the study period. * Receipt of any immunoglobulins and/or any blood products within 3 months of study enrollment or planned administration of any of these products during the study period. * Any known or suspected allergy to any constituent of influenza vaccines. * Known pregnancy or a positive urine beta-human chorionic gonadotropin (ß-hCG) test result prior to dosing on Study Days 0 or 21. * Lactating or nursing. * Women of child bearing potential who lack a history of reliable contraceptive practices. * Known receipt of analgesic or antipyretic medication on the day of treatment