1. Problem of Interest We are proposing to study the effectiveness of vaccines in people who are taking drugs that affect the immune system. There are many populations of people who have chronic medical conditions that require them to have long-term treatment with immunosuppressive medications (drugs that decrease the function of the immune system). Examples of these patients include organ transplant recipients, patients with immune cell cancers such as leukemia and lymphoma, patients with inflammatory disorders such as lupus or scleroderma, and patients with skin conditions requiring steroid-based creams, ointments, pills, or injections. Patients who are taking these medications should receive appropriate vaccinations such as tetanus boosters, influenza vaccines, and pneumonia vaccines. The effectiveness of vaccinations depends in large part on a strong response to the vaccine by the immune system. Drugs that decrease immune system function therefore, may also decrease the effectiveness of vaccines.