Influenza in People With Normal and Weakened Immune Systems

Overview

This study will evaluate how the immune system responds to influenza infection and compare how the infection differs in patients with a weakened immune system versus those with a healthy immune system. Patients at the NIH Clinical Center who are older than 2 years of age and who are diagnosed with influenza A or B may be eligible for this study. Patients with healthy immune systems and weakened immune systems are included. Participants answer questions about how they are feeling and have a physical examination to evaluate their symptoms. Blood and nasal fluid are collected on the first day and then every other day for a total of 8 days. Nasal fluid is collected by either inserting a small tube in the nose and washing the nose with salt water and collecting the fluid obtained, or by rubbing the inside of the nose with a swab. Physical examinations are repeated on the days that blood and nasal fluid are collected.

Influenza viruses cause significant morbidity each year, and past epidemics and pandemics have caused significant mortality. The impact influenza has or could have on the increasing number of patients who are immunocompromised due to acute and chronic diseases as well as immunosuppressive therapies is largely unknown. Limited information is available about the innate immune response to influenza and how chronic illness and immunosuppression may affect the immune response to the virus in comparison to that seen in normal hosts. We will evaluate both immunocompromised and non-immunocompromised (control group) patients from the local community, and the NIH Clinical Center. Patients with known or suspected influenza will be evaluated by recording their symptoms, collecting their blood and nasal specimens, and isolating their viruses. Each patient s infection will be mapped by performing genomic analysis of the viral isolates collected during the patient s infection (which will include analysis of sequences known to confer resistance to antiviral medication), measuring cytokine levels in blood and nasal mucosal samples, and measuring influenza-specific antibody responses. Correlation of these results with clinical symptoms and clinical outcomes will be evaluated. Elucidation of these responses and the genomic changes the virus may undergo during infection and treatment for influenza in both normal and immunocompromised patients may help to better understand the impact influenza has on the overall health of patients, as well as what strategies may be performed to better protect or treat patients during the emergence of a new pandemic.