A Study of Post COVID-19 Mechanisms for Chronic Lung Sequelae

Inclusion Criteria:

For the Sequelae Group

* Age ≥18 years at screening, PCR confirmed COVID19 illness (+PCR defines day 0 of illness), hospitalization for COVID-19, absence of pre-existing history of interstitial lung disease, or significant other lung disease.
* Severity of illness will be categorized as moderate disease (supplemental oxygen need 1-8L at any time during hospitalization), severe disease (need for high flow oxygen delivery ≥8L at any time during hospitalization) and critical illness (need for ICU admission or mechanical ventilation).

Control Recovery Group

* Age ≥18 years at screening
* PCR confirmed COVID-19 cases who had nonsymptomatic or mild acute infection that do not require hospitalization 7,48,49
* Absence of pre-existing history of interstitial lung disease, or significant other lung disease, absence of any ongoing respiratory and systemic symptoms.

Exclusion Criteria:

* Inability to provide informed consent, evidence of pre-existing interstitial lung disease or chronic lung disease;
* Active cigarette smoking, vaping or other inhalation use.
* Immunocompromised host status due to ongoing therapy with methotrexate, CellCept, azathioprine, rituximab, cyclophosphamide or other biologic agents;
* \> 20 pack year smoking history.
* History of chemotherapy or radiation therapy in the last two years; and pregnancy.