Influenza virus is an important cause of morbidity in the transplant population and can lead to viral and bacterial pneumonia and contribute to the development of rejection. Although the annual influenza vaccine is recommended for transplant patients, studies have shown that a single intramuscular dose has poor immunogenicity. There are no studies that define the effect of intradermal doses in this population. We plan to study the immunogenicity of two different administration routes of the influenza vaccine in 200 solid organ transplant patients during the 2010-2011 season. Patients will be randomized to receive influenza vaccine either intradermally or intramuscularly. We hypothesize that the patients who receive the intradermal influenza vaccine will significantly reach a higher response to the vaccine. This study advances research on the prevention of serious viral infections in transplant recipients. Results from this study have the potential to directly improve patient care. If the use of the intradermal influenza vaccine is successful, this strategy may lead to a significant reduction in burden of disease, hospitalizations, and long-term morbidity.

Inclusion Criteria:

• Age ≥ 18 and ≤ 59,
• Greater than 3 months post-transplant,
• Any solid organ transplant (kidney, liver, heart, lung, pancreas, intestinal or combinations of the aforementioned organs)

Exclusion Criteria:

• Has already received influenza vaccination for 2010-2011 season;
• Egg allergy,
• Previous life-threatening reaction to influenza vaccine (i.e. Guillain Barre Syndrome),
• Ongoing therapy for rejection,
• Febrile illness in the past two weeks,
• Unable to provide informed consent,
• Unable to comply with study protocol