A Pilot Study of Influenza Viruses Isolated From Immunocompromised Children and Adolescents

Participants will have nasal, oral and stool specimens obtained at the time they are diagnosed with influenza infections, and 7, 14, 21 and 28 days later. The genome of influenza viruses that are isolated from these participants will be sequenced and compared to one another and to standard influenza strains. PRIMARY OBJECTIVE: * To determine the proportion of pediatric oncology patients with nasal and oropharyngeal shedding of influenza viruses at 7, 14, 21 and 28 days following the diagnosis of infection. SECONDARY OBJECTIVES: * To determine the proportion of gastrointestinal shedding of human influenza viruses. * To determine the frequency and pattern of mutations in influenza viruses isolated from pediatric oncology patients. * To explore the biological consequences of mutations in influenza viruses isolated from pediatric oncology patients.