Inclusion criteria for COVID-19 participants: 1. Aged 18 years and older. 2. Hospitalised with confirmed COVID-19 respiratory infection by swab-positive PCR with hypoxia (SpO2 less than or equal to 93% on room air) requiring oxygen therapy. 3. Patients that score 4-5 on the WHO COVID Ordinal Scale for Clinical Improvement. 4. Willing and able to comply with all study requirements, including treatment, timing and/or nature of required assessments. 5. Signed, written informed consent from the participant. Inclusion criteria for non-COVID-19/ARDS participants: 1. Aged 18 years and older. 2. Hospitalised with non-COVID-19 ARDS with hypoxia (SpO2 less than or equal to 93% on room air) requiring oxygen therapy. 3. Willing and able to comply with all study requirements, including treatment, timing and/or nature of required assessments. 4. Signed, written informed consent from the participant.

Inclusion criteria for COVID-19 participants: 1. Aged 18 years and older. 2. Hospitalised with confirmed COVID-19 respiratory infection by swab-positive PCR with hypoxia (SpO2 less than or equal to 93% on room air) requiring oxygen therapy. 3. Patients that score 4-5 on the WHO COVID Ordinal Scale for Clinical Improvement. 4. Willing and able to comply with all study requirements, including treatment, timing and/or nature of required assessments. 5. Signed, written informed consent from the participant. Inclusion criteria for non-COVID-19/ARDS participants: 1. Aged 18 years and older. 2. Hospitalised with non-COVID-19 ARDS with hypoxia (SpO2 less than or equal to 93% on room air) requiring oxygen therapy. 3. Willing and able to comply with all study requirements, including treatment, timing and/or nature of required assessments. 4. Signed, written informed consent from the participant.