Jet Injection for Influenza

Inclusion Criteria: * Adults aged ≥18 and ≤64 years of age at the time of enrollment * Willing and able to give informed consent after reading the consent form and adequate opportunity to discuss the study with the investigator or qualified designee * Willing and able to adhere to all protocol required study procedures and to attend scheduled visits. * Able to receive the TIV influenza vaccine, based on University of Colorado Health (UCH) employee health flu screening guidelines. * Stable health status with no exclusionary medical or neuropsychiatric conditions as determined during the screening evaluation and based on the clinical judgment of the investigator or qualified designee. * Access to a consistent means of telephone contact Exclusion Criteria: * Presence of any febrile illness (oral temperature \>38°C) on the day of immunization. Such subjects will be reevaluated for enrollment after resolution of illness. * Presence of significant acute or chronic uncontrolled medical or neuropsychiatric illness and /or presence of any significant condition that may prohibit inclusion as determined by the investigator or his qualified designee. Uncontrolled is defined as: requiring institution of a new treatment within 1 month prior to study enrollment or change in medication dosage in the month prior to study enrollment. * Any immunosuppressive condition including: history of HIV infection, cancer or cancer treatment within 3 years of study enrollment, systemic glucocorticoids (in a dose ≥10 mg prednisone daily or equivalent for more than 7 consecutive days or for 10 or more days in total) within 1 month of study enrollment, or any other cytotoxic or immunosuppressive drug within 3 months of study enrollment. Any significant disorder of coagulation that would increase the risk of intramuscular injections or treatment with Coumadin derivatives or heparin. * Known or suspected to be allergic to eggs, chicken protein, gentamicin or influenza vaccine. * History of severe or previous serious adverse reaction after an influenza vaccination. * Receipt of any immunoglobulin and/or blood products within 3 months of immunization or planned administration of any of these products during the study period. * Prior history of any demyelinating disease including Guillain-Barre syndrome. * Presence of an active neurological disorder. * History of significant alcohol or drug abuse within one year prior to study enrollment. * Influenza vaccination or laboratory confirmed influenza infection within the previous six months before study vaccination or planned influenza vaccination during the study period. * Planned administration of any non-influenza vaccines 30 days prior to the study or during the study period. * Pregnant or plans to become pregnant during the study period. * Currently enrolled in another vaccine or drug study.