Better understanding of the immune responses to influenza vaccination is needed in order to understand situations of poor vaccine response. Adults will receive influenza vaccination and then have peripheral blood drawn at pre-defined intervals in order to study the lymphocyte responses.

Inclusion Criteria:

• Community-dwelling adults able to provide consent who need influenza vaccination for standard of care

Exclusion Criteria:

• febrile illness at time of vaccination
• active malignancy
• use of immunosuppressing medications
• blood donation in the past 60 days
• influenza vaccinated during the preceding 6 months
• allergic reactions to influenza vaccination