Background: Respiratory viruses, like the flu or COVID-19, cause significant illness and death worldwide. Researchers want to collect samples from people with respiratory virus infections. The samples in this natural history study will be used in future research.

Objective: To obtain samples from people with respiratory viruses to learn more about respiratory virus infections and the immune responses against them.

Eligibility: People aged 3 and older who have or are suspected to have a respiratory virus infection.

Design: Participants will be screened with a medical record review. Participants will give blood samples. Data from their medical records will be collected. Participants will give nose samples. A soft plastic strip will be put into each nostril for a minute. They may also give nose, mouth (back of the throat), or saliva samples using swabs. Participants may receive kits by mail to collect nose and blood samples at home. They will use soft plastic strips to collect nose samples. To collect blood, they will prick their finger and dab a few drops of blood on four plastic tips. If a participant is in the hospital, air samples may be collected in their room. Participation will last for up to 2 years. After 2 years, participants may be asked for their consent again to give new samples and new medical data.