COVID-19 Longitudinal Biomarkers in Lung Injury (COLOBILI)

• Primary Cohort: Patients admitted to the ICU with respiratory deterioration suspected or confirmed to be due to SARS-CoV-2. Suspicion will be based on the clinical criteria in place at SMH, with the threshold for inclusion being a suspicion high enough to use PPE until confirmatory testing results are obtained. Only patients found to be COVID19 positive will stay in this cohort. This population will be called "ICU Positive".
• Secondary Cohort: Patients admitted to the ICU for any reason who are COVID19 positive, regardless of admission date or when they are found to be COVID19 positive. This population will be called "ICU Positive - delayed"
• Biological controls in the ICU: Any patients from the primary cohort who are found to be COVID19 negative. This population will be called "ICU negative".
• Biological controls outside the ICU: Patients admitted to the floor with respiratory deterioration suspected or confirmed to be due to SARS-CoV-2, or that develop such respiratory deterioration within 15 days of admission (i.e. become "persons under investigation"). Suspicion will be based on the clinical criteria in place at SMH, with the threshold for inclusion being a suspicion high enough to use PPE until confirmatory testing results are obtained. Only patients found to be COVID19 positive will stay in this cohort. If these patients require ICU admission within 15 days, they will cross-over to the "ICU positive" cohort and count towards that cohort (i.e. number of recruited patients). If they don't require ICU admission within 15 days, they will stay in this cohort and be called "never ICU".
• Healthy volunteers: The investigators will recruit healthy volunteers among healthcare workers and allied personnel in the hospital. They will provide peripheral blood to serve as: a) independent controls for experimental and laboratory variables, and b) references of healthy baseline state for experiments.
• A patient previously enrolled as a COVID negative can be re-enrolled in a subsequent hospitalization with a new study ID (i.e. counts as another encounter for the total enrollment). The records will be linked to indicate they represent the same person enrolled again.

Exclusion Criteria

• Refusal to participate.
• Inability to record the primary outcome during the first 2 weeks.
• For the ICU positive and ICU negative cohorts only: failure to obtain the day 0 or 1 blood sample (for example technical problems, or identification of COVID-19 after ICU admission i.e. there was no suspicion on admission).
• For the ward patients, inability to collect day 1 or 2 blood sample.
• Known to have had COVID in the past (>4 weeks) in any setting.
• Healthy volunteers only: COVID19 known or suspected infection, or unprotected exposure to a known acutely ill COVID19 patient in the past 4 weeks; and/or currently unwell or in the course of an acute illness.