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.

• 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.