inclusion criteria: * signed informed consent * pcr positive for covid-19 within the last 4 days * hospitalized * spo2 ≤ 93% on room air or requiring supplemental oxygen at screening (i.e. patients with severe disease) * lymphopenia (total lymphocyte count \< 1.5 × 109/l)

inclusion criteria: * signed informed consent * pcr positive for covid-19 within the last 4 days * hospitalized * spo2 ≤ 93% on room air or requiring supplemental oxygen at screening (i.e. patients with severe disease) * lymphopenia (total lymphocyte count \< 1.5 × 109/l)

inclusion criteria: - signed informed consent - pcr positive for covid-19 within the last 4 days - hospitalized - spo2 ≤ 93% on room air or requiring supplemental oxygen at screening (i.e. patients with severe disease) - lymphopenia (total lymphocyte count < 1.5 × 109/l)

inclusion criteria: - signed informed consent - pcr positive for covid-19 within the last 4 days - hospitalized - spo2 ≤ 93% on room air or requiring supplemental oxygen at screening (i.e. patients with severe disease) - lymphopenia (total lymphocyte count < 1.5 × 109/l)