This is a multi-center, observational study that will enroll 1) patients with severe COVID-19 who have agreed to undergo therapy with Seraph® 100 under the existing EUA; 2) patients (medical record data) that have been previously treated with the Seraph® 100 after the date of the EUA approval (17 April 2020), but before the date that the study is approved at the study site, and 3) a convenience sample of patients (medical record data) in a historical control group who were admitted to the ICU at participating sites with severe COVID-19 infection, meeting the EUA treatment criteria, but not treated with Seraph® 100 up to the time the PURIFY-OBS protocol is approved at the site

This is a multi-center, observational study that will enroll 1) patients with severe COVID-19 who have agreed to undergo therapy with Seraph® 100 under the existing EUA; 2) patients (medical record data) that have been previously treated with the Seraph® 100 after the date of the EUA approval (17 April 2020), but before the date that the study is approved at the study site, and 3) a convenience sample of patients (medical record data) in a historical control group who were admitted to the ICU at participating sites with severe COVID-19 infection, meeting the EUA treatment criteria, but not treated with Seraph® 100 up to the time the PURIFY-OBS protocol is approved at the site

At the time of protocol approval, data from all patients who have been treated up until that date will be collected retrospectively. Patients who meet the treatment criteria and are identified as candidates for Seraph® 100 with plans for treatment initiation will be enrolled prospectively after informed consent has been obtained. Biospecimen collection (blood, urine, sputum, swabs) will be planned for prospectively enrolled patients at various time-points. However, if subjects do not want to contribute samples, they will be given the option of contributing only their clinical data for analysis. Specific Seraph® 100 treatment procedures will be determined by each individual site. Recommendations for treatment related procedures are provided by the company. Additionally, among sites participating in PURIFY-OBS, all patients who met EUA treatment criteria but were NOT initiated on therapy will be enrolled retrospectively into a historical control group. Procedures for identifying study subjects will be as follows:

Retrospective Seraph® 100 As noted in the inclusion/exclusion criteria, this group will be composed of subjects that were treated with Seraph® 100 after the date of the EUA approval (17 April 2020), but before the date that the study is approved at the study site. To identify patients, the site investigator will query 1) institution's electronic medical record for critical ill patients treated with Seraph® 100 and 2) attending intensive care physicians and nephrologists who have provided care to critically ill patients with COVID-19. A waiver of informed consent will be requested from the Institutional Review Board (IRB) to allow the collection of these retrospective data.

Prospective Seraph® 100 To identify prospective Seraph® 100 patients, the individual site investigators will review currently admitted ICU patients for inclusion criteria #1and #2 (see above). The study team will then ask the physician caring for the patient to contact the study team should the patient require therapy with Seraph® 100. Additionally, the study team will review the medical records of admitted patients to see if they have recently been started on Seraph. Patients found to meet inclusion/exclusion criteria (or their LARs) will be offered the opportunity to sign an informed consent and participate in the study. Note that patients that were started on Seraph® 100 before the date of approval for a study site, but are still admitted, will not be eligible to give biospecimens. However, they will be given the option of signing an informed consent so that their data can be used in the study.

Historical Control Our historical control group will be a sample of convenience, composed of patients admitted to the ICU at participating sites with severe COVID-19 infection, meeting the EUA treatment criteria, but not treated with Seraph® 100 up to the time the PURIFY-OBS protocol is approved at the site. The individual site investigators will be responsible for querying their institution's electronic medical records to identify critically ill patients with COVID-19 admitted from the date of EUA approval (17 April 2020) until the date the protocol was approved at their study site. These records will then be further examined by the local study team to ensure that the patients meet the inclusion/exclusion criteria detailed above. Note that patients will be excluded if they are still admitted to the hospital on or after the date that the protocol was approved at that study site. A waiver of informed consent will be requested from the Institutional Review Board (IRB) to allow the collection of these retrospective data.

Study Timeline Each included subject's medical record will be reviewed from the time of hospital admission through hospital discharge. Enrollment will be conducted over a 2-year period (up to 200 patients total including both retrospective and prospective patients). For prospective patients who consent, biospecimen (blood, urine, sputum) will be collected before initiation of extracorporeal treatment, 1 hour following treatment, as well as days 1, 2, 3, 4, 7, 28 and 90-180

Inclusion Criteria:

Prospective Seraph® 100

1. Subject must be 18 years of age
2. Per the FDA Approve EUA:

Subject must have confirmed COVID-19 infection and be admitted to the ICU with confirmed or imminent respiratory failure and any one of the following conditions:

1. Early acute lung injury (ALI)/early acute respiratory distress syndrome (ARDS); or

2. Severe disease, defined as:

   1. Dyspnea,
   2. Respiratory frequency ≥ 30/min,
   3. Blood oxygen saturation ≤ 93%,
   4. Partial pressure of arterial oxygen to fraction of inspired oxygen ratio <300, and/or
   5. Lung infiltrates > 50% within 24 to 48 hours; or

3. Life-threatening disease, defined as:

   1. Respiratory failure,
   2. Septic shock, and/or
   3. Multiple organ dysfunction or failure. 2. Prospective study patients (or their Legally Authorized Representative (LAR)) provides informed consent. Patients or their legally authorized representative will be consented in their main language if they are not fluent in English.

   3. Prospective study patient is willing to complete all study visits as required by the protocol 4. For Military Treatment Facility (MTF) enrollment only - must be DEERS eligible for care at the MTF

Retrospective Seraph® 100

1. Subject must be 18 years of age

2. Per the FDA Approve EUA:

   Subject must have confirmed COVID-19 infection and be admitted to the ICU with confirmed or imminent respiratory failure and any one of the following conditions:

   1. Early acute lung injury (ALI)/early acute respiratory distress syndrome (ARDS); or

   2. Severe disease, defined as:

      1. Dyspnea,
      2. Respiratory frequency ≥ 30/min,
      3. Blood oxygen saturation ≤ 93%,
      4. Partial pressure of arterial oxygen to fraction of inspired oxygen ratio <300, and/or
      5. Lung infiltrates > 50% within 24 to 48 hours; or

   3. Life-threatening disease, defined as:

      1. Respiratory failure,
      2. Septic shock, and/or
      3. Multiple organ dysfunction or failure.

3. Treated with Seraph® 100 from 17 April 2020 (date of EUA approval) to the date of study approval at the study site.

Historical Control

1. Subject must be 18 years of age

2. Per the FDA Approve EUA:

   Subject must have confirmed COVID-19 infection and be admitted to the ICU with confirmed or imminent respiratory failure and any one of the following conditions:

   1. Early acute lung injury (ALI)/early acute respiratory distress syndrome (ARDS); or

   2. Severe disease, defined as:

      1. Dyspnea
      2. Respiratory frequency ≥ 30/min,
      3. Blood oxygen saturation ≤ 93%,
      4. Partial pressure of arterial oxygen to fraction of inspired oxygen ratio <300, and/or
      5. Lung infiltrates > 50% within 24 to 48 hours; or

   3. Life-threatening disease, defined as:

   1. Respiratory failure,
   2. Septic shock, and/or
   3. Multiple organ dysfunction or failure.

3. Hospitalized from 20 January 2020 to the date of study approval at the study site.

Exclusion Criteria:

Prospective

1. Unwilling to provide informed consent
2. Unable to provide informed consent and no LAR available to provide permission

Retrospective No specific exclusion criteria. However, patients treated with Seraph® 100 prior to approval of the study at a site and who remains admitted to the hospital at the time the study is approved, will be given the opportunity to participate in the study by signing consent for their health data to be collected (and not biospecimens).

Historical Controls:

Patients who remain admitted to the hospital at the time that the study is approved at the study site will be excluded.

This multi-center, observational study will attempt to recruit all patients treated with the Seraph® 100 under EUA #200165 in the United States at both civilian and military hospitals.