The study is a prospective single site exploratory study to examine the impact of Food and Drug Administration (FDA) approved seasonal flu vaccine on the immune responses of H5N1 vaccine previously received with or without the AS03 adjuvant.

Influenza, caused by the influenza virus, is a contagious respiratory disease that can result in mild to severe illness. It is estimated that up to 80,000 deaths and approximately 200,000 Americans are hospitalized annually due to complications. Vaccination is the most effective way of controlling flu and preventing its illness and complications; however, antibody responses to seasonal influenza vaccines decrease over time and only target a small number of antibody binding sites In 2015, the Hope Clinic of the Emory Vaccine Center completed a study analyzing human immune responses to a pandemic H5N1, or "bird flu" vaccine, either alone or combined with the GlaxoSmithKline adjuvant system 03 (AS03).

Participants that took part in the 2013 HIPCVAX-010 Systems Biology of Influenza A (H5N1) Virus Monovalent Vaccine with and without AS03 Adjuvant study will be enrolled in this study to assess the effect of seasonal influenza vaccine in shaping the immune responses. The study aims to address important immunological mechanisms that can assist scientists in the creation of a universal influenza vaccine.

Inclusion Criteria:

• Participated in HIPCVAX-010 Systems Biology of Influenza A (H5N1) Virus Monovalent Vaccine with and without AS03 Adjuvant study.
• Capable of informed consent and provision of written informed consent before any study procedures.
• Capable of attending all study visits according to the study schedule.
• Are in good health, as determined by medical history and targeted physical exam related to this history.
• Female subjects of childbearing age must have a negative urine pregnancy test before study vaccination, and must use at least one form of contraception to avoid pregnancy for 28 days before and 28 days after Fluarix Quadrivalent administration.

Exclusion Criteria:

• Have an acute illness, including any fever (> 100.4 F [> 38 degrees C], regardless of the route) within 72 hours before vaccination.
• Have any acute or chronic medical condition that, in the opinion of the principal investigator, would make vaccination unsafe or interfere with the evaluation of immune response to study vaccination.
• Alcohol or drug abuse and psychiatric conditions that, in the opinion of the investigator, would preclude compliance with the trial or interpretation of safety or endpoint data.
• Have a suppressed immune system as a result of illness, immunosuppressive medication, chemotherapy, or radiation therapy within 3 years prior to study vaccination.
• Are pregnant or breastfeeding or plan to within one month of vaccination.
• Have taken oral or parenteral corticosteroids of any dose within 28 days before study vaccination.
• Have a known history of autoimmune disease.
• Have a history of Guillain-Barre Syndrome.
• Have a history of bleeding disorders.
• Have known hypersensitivity or allergy to any component of the vaccine, including egg and latex allergies, or history of anaphylaxis with influenza vaccine or vaccine component.
• Have received blood or blood products 3 months prior to study entry or expected to receive through 6 months after study entry.
• Have received any live virus vaccines within 4 weeks prior to study entry or expected receipt within 4 weeks after study entry.
• Have received any inactivated vaccine within 2 weeks or expected receipt within 2 weeks after study entry.
• Have received any experimental agents within 6 weeks prior to study or plan to through study duration.
• Have received the 2018-2019 influenza seasonal vaccine.
• Documented influenza infection during the 2018-2019 influenza season.
• Social, occupational, or any other condition that in the opinion of the investigator might interfere with compliance with the study and vaccine evaluation.

from Day 1 post vaccination to Day 365 post vaccination