A Pilot Study to Assess the Immunogenicity and Reactogenicity of High Versus Standard Dose TIV

Inclusion Criteria: 1. 18-64 years old, inclusive, as of October 1st of year of enrolment; 2. Healthcare worker, broadly defined as a person either providing health care, or working in an acute care hospital or long term healthcare facility; 3. Has access to email and the internet for adverse event reporting, or is willing to complete forms on paper and deliver to the site study office; 4. Understand the study, agree to its requirements, and give written consent; Exclusion Criteria: 1. Receipt of influenza vaccine for the current northern hemisphere season prior to randomization; 2. Serious adverse event to a previous dose of influenza vaccine; 3. Immunoglobulin E mediated allergic reaction to a previous dose of influenza vaccine or to any excipients in the study vaccines 4. Previous episode of Guillain-Barré syndrome with 6 weeks of receiving an influenza vaccine; 5. Receipt of immunoglobulins, blood or blood-derived products in the past 3 months; 6. Receipt of another vaccine, or initiation of new medication, or hospital admission for any reason within the 30 days prior to the study dose of vaccine 7. Plans to receive any vaccine, initiate any medication, or be admitted to hospital before day 21 after vaccination (visit 2); 8. Known or suspected congenital or acquired immunodeficiency (including HIV infection); or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months) 9. Any condition, including but not limited to drug and alcohol addiction, which, in the opinion of the investigator might interfere with the ability to comply with trial conduct or completion; 10. Moderate or severe acute illness or active infection or fever (temperature ≥37.8oC) on the day the vaccine dose is due (participant may receive dose of vaccine 48 hours after symptoms have resolved and body temperature has returned to normal without the use of antipyretics.