Unlike most influenza viruses, the 2009 H1N1 virus has affected people between 5 and 40 years old more often than people 60 years old or older. It may be that older people have had greater exposure to previous strains of H1N1 influenza, and this previous exposure protects them from infection. This study will examine how older people respond to a version of the H1N1 virus vaccine that includes a live, noninfectious version of the virus.

Unlike most influenza viruses, the 2009 H1N1 virus affects many individuals between 5 and 40 years old, but very few 60 years old or older. It is not completely understood why, but scientists believe it may be because older people may have been exposed to other H1N1 viruses in their lives. H1N1 viruses were common until 1957, when they were eclipsed by H2N2 viruses.

In order to test susceptibility to the 2009 H1N1 virus, this study will examine how often people older than 60 get infected by the 2009 H1N1 live attenuated influenza vaccine (LAIV). The LAIV is made from a live virus that has been weakened, so the ability of the immune system to combat this weakened form is likely to mimic its ability to combat the normal form. Additionally, this study will examine how LAIVs work in older people; inactivated virus vaccines are used more often than LAIVs in older people, so little is known of LAIV's effects on this population.

Participation in this study will last 6 months. Participants will be people older than 60, divided into equal groups of people between the ages of 60 and 70 and people older than 70. Both groups will receive one dose of LAIV for 2009 H1N1 vaccine.

There will be six study visits, occurring at baseline and 2, 5, 7, 28, and 180 days after vaccination. Nasal wicks and throat swabs will be taken on Days 2, 5, and 7; a nasal wick alone will be taken at baseline and on Day 28. Blood samples will be taken at baseline and on Days 7 and 28. Participants will undergo physical exams at each visit.

Inclusion Criteria:

• No prior history of infection with novel H1N1 virus or immunization with novel H1N1 vaccine documented by a laboratory
• Female participants must not be capable of becoming pregnant or take steps to prevent pregnancy from 30 days before enrollment to 30 days after receiving the study vaccine
• In good health, as determined by medical history and targeted physical examination
• Able to understand and comply with the planned study procedures, including being available for all study visits

Exclusion Criteria:

• Pregnancy
• Previous history of vaccination against novel H1N1 virus or a laboratory documented history of previous novel H1N1 infection
• Immunosuppressed as a result of an underlying illness or treatment with immunosuppressive or cytotoxic drugs or use of anticancer chemotherapy or radiation therapy within the preceding 36 months
• Active neoplastic disease (excluding nonmelanoma skin cancer or prostate cancer that is stable in the absence of therapy) or a history of any hematological malignancy. For this criterion, "active" is defined as having received treatment within the past 5 years.
• Long-term (greater than 2 weeks) use of oral or parenteral steroids or high-dose inhaled steroids (greater than 800 mcg/day of beclomethasone dipropionate or equivalent) within the 6 months prior to study enrollment (nasal and topical steroids are allowed)
• Received immunoglobulin or another blood product within the 3 months prior to enrollment in this study
• Received an inactivated vaccine within 2 weeks or a live vaccine within 4 weeks prior to enrollment in this study or plans to receive another vaccine within the next 28 days
• Has an acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses.
• Has had an acute illness or an oral temperature greater than 99.9°F (37.7°C) within 3 days prior to enrollment or vaccination. Subjects who had an acute illness that was treated with symptoms resolved are eligible to enroll as long as treatment is completed and symptoms are resolved more than 3 days prior to enrollment.
• Currently participating or plans to participate in a study that involves an experimental agent (vaccine, drug, biologic, device, blood product, or medication), has received an experimental agent within 1 month prior to enrollment in this study, expects to receive another experimental agent during participation in this study, or intends to donate blood during the study period
• History of alcohol or drug abuse in the 5 years prior to enrollment
• Has a known human immunodeficiency virus (HIV) or hepatitis B or C infection
• Has a previous history of Guillain-Barré syndrome
• Allergic to eggs or egg proteins, gentamicin, gelatin, or arginine or has experienced life-threatening reactions to previous influenza vaccination
• Has any other condition that would, in the opinion of the site investigator, place the participant at an unacceptable risk of injury or render the participant unable to meet the requirements of the protocol

Adverse Events were collected from day 0 thru Dy 180