Effects of Aging on Primary and Secondary Vaccine Responses in a 15-Year Longitudinal Cohort

Inclusion Criteria:

   1. Provision of signed and dated informed consent form

   2. Stated willingness to comply with all study procedures and availability for the
   duration of the study.

   3. Prior participant in either the Ellison cohort or another Stanford vaccine study with
   archived samples.

   4. Male or female, aged 18-40 years or 65 years and older.

   5. In good general health as evidenced by medical history.

Exclusion Criteria:

   1. Prior off-study vaccination with the current season influenza vaccine for influenza
   vaccinations.

   2. Allergy to egg or egg products

   3. Allergy to vaccine components, including thimerosal

   4. Active systemic or serious concurrent illness, including febrile illness on the day of
   vaccination

   5. Receipt of blood or blood products within the past 6 months of any study vaccination
   or planned receipt of blood products prior to completion of Day 28 post-immunization
   visit.

   6. Receipt of inactivated vaccine 14 days prior to study vaccination or planned
   vaccination prior to Day 28 after study vaccination.

   7. Receipt of live, attenuated vaccine within 60 days of study vaccination or planned
   vaccination prior to Day 28 after study vaccination.

   8. Donation of the equivalent of a unit of blood within 6 weeks prior to enrollment or
   planned blood donation prior to Day 28 after study vaccination.

   9. Use of investigational agents within 30 days prior to enrollment or planned use of
   investigational agents prior to completion of all study visits.

10. Need for allergy immunizations (that cannot be postponed) between Days 0 and 28
   post-immunization.

11. Pregnant or lactating woman for all but influenza vaccine. A woman who is pregnant or
   breastfeeding may be evaluated by the Protocol Director to determine if influenza
   vaccination would affect volunteer safety and may be included at the discretion of the
   investigator. Blood sample collection will be adjusted as necessary for volunteer
   safety (e.g. blood collection volume for a pregnant woman would follow the minimal
   risk guidelines of 50 ml in an 8 week period and collection may not occur more
   frequently than 2 times per week).

12. Any condition, which, in the opinion of the investigator, might interfere with
   volunteer safety, study objectives or the ability of the participant to understand or
   comply with the study protocol.