Low Pathogenicity Avian H10N7 Influenza Virus in a Healthy Human Challenge Model

Background: Influenza, also called flu, is a virus. It can cause mild symptoms such as fever, cough, sore throat, and aches. Sometimes, flu can cause serious complications. Researchers want to see how people s immune systems respond to the flu. Objective: To find the smallest dose of influenza H10N7 virus that may cause an uncomplicated mild to moderate flu infection in healthy people. This dose will be used in the future to test how well new flu vaccines work. Eligibility: Healthy adults age 18-50. Design: Participants will be screened with: Physical exam with vital signs and weight Medical and medicine review Blood and urine tests Electrocardiogram to measure the heart s electrical activity. Screening tests will be repeated during the study. Participants will be tested for SARS-CoV-2 and other respiratory infections. For this, a swab will be inserted into the back of the nose. Participants will be admitted to an isolation room in the Clinical Center. They will stay in the hospital for at least 10 days. They will not have visitors. Participants may have a heart ultrasound. They may have lung function tests. For this, they will blow into a tube to measure lung capacity. One dose of the flu virus will be sprayed into participants nostrils. Participants will be monitored 24 hours a day. They will give nasal samples (using nasal washes and brushes) and blood samples almost every day. They will complete surveys about their symptoms. Participants will be discharged after they have 2 consecutive negative tests for flu. Participants will have at least 4 follow-up visits: 1 visit every 2 weeks for 8 weeks.