Inclusion Criteria:

- Participants must have presented with acute, symptomatic seasonal influenza or
SARS-CoV-2 infection proven by an approved CLIA certified test and be enrolled in
study while still symptomatic or within 72 hours of the resolution of viral
respiratory illness symptoms.

- Alternatively, uninfected participants in the control cohort must have received an
FDA-approved seasonal influenza and/or SARS-CoV-2 vaccine within the past 12 months
and not experienced a documented influenza or SARS-CoV-2 infection since receiving
that most recent vaccine dose.

- Participants must be able to understand and provide full written informed consent.

- Participants must be male or female between the ages of 18 and 60.

- Participants must be in stable health, as determined by medical history and targeted
physical exam related to that history.

Exclusion Criteria:

- Co-infection with any respiratory virus in addition to the index influenza or
SARS-CoV-2 infection on a multi-plex viral testing panel.

- Severe illness with anticipated need for hospitalization for the index infection.

- Current or previous diagnosis of an immunocompromising condition.

- Receipt of systemic immunosuppressants or immune-modifying drugs for > 14 days in
total within 6 months prior to screening or is anticipating the need for
immunosuppressive treatment at any time during study participation.

- Current symptomatic acute or unstable chronic disease requiring medical or surgical
care, to include significant change in therapy or hospitalization, at the discretion
of the investigator. Any known diagnosed chronic pulmonary, cardiovascular, renal,
hepatic, hematologic, or metabolic disorder with the exception of isolated treated
hypertension.

- Known chronic neurologic or neurodevelopmental condition including spinal cord
injury with resultant weakness of any kind (this does not exclude patients with
chronic back pain or previous disk herniation/back surgery, only patients with
documented weakness, quadriplegia or paraplegia). This exclusion criterion does not
exclude from the study individuals with recurrent migraine headaches as their only
chronic neurologic condition.

- Active cancer diagnosis, including any cancer that has not been in remission for at
least 1 year. Isolated basal or squamous cell skin cancers are not excluded.

- History of excessive alcohol consumption, drug abuse, psychiatric conditions, social
conditions, or occupational conditions that in the opinion of the investigator would
preclude compliance with the study.

- Body Mass Index (BMI) > 40

- Pregnant women and nursing mothers or women who are planning to become pregnant
during the study interval.

- Have donated blood, blood products or bone marrow within 30 days before study entry
or plan to donate blood at any time during the duration of study participation or up
to 30 days after the last study blood draw.

- Current ongoing participation in a clinical trial evaluating an investigational
agent, unless the trial is in follow-up only and the last dose of the
investigational agent was taken > 30 days or > 5 half-lives prior to enrollment,
whichever is greater.

- Any condition in the opinion of the investigator that would interfere with the safe
and proper conduct of the study.

For participants willing to undergo bronchoscopy:

- Coagulopathy as defined by screening safety labs that reveal an INR > 1.4, at PTT >
40, or a platelet count < 100,000 precludes participation in the bronchoscopy
procedure.

- Evidence of ongoing significant pulmonary disease on the day of bronchoscopy,
including pulse oximetry with oxygen saturation of 92% or less on room air, or
infiltrate or pleural effusion noted on an upright PA and lateral chest x-ray
performed on the day of bronchoscopy.

- Allergy or contraindication to anesthesia for participants willing to undergo
bronchoscopy.