Here is the design of a clinical trial:

Official Title: DEXamethasone EARLY Administration in Hospitalized Patients With Covid-19 Pneumonia and High Risk of Developing Acute Respiratory Distress Syndrome

Included conditions:
- COVID-19
- Acute Respiratory Distress Syndrome
- Pneumonia, Viral

Study Armgroups:
- {'label': 'Dexamethasone', 'type': 'EXPERIMENTAL', 'description': 'Dexamethasone base 6 mg once daily for seven days', 'interventionNames': ['Drug: Dexamethasone']}
- {'label': 'Standard of care', 'type': 'ACTIVE_COMPARATOR', 'description': 'Standard care therapy', 'interventionNames': ['Drug: Dexamethasone']}

Interventions:
- {'type': 'DRUG', 'name': 'Dexamethasone', 'description': 'Dexamethasone base 6 mg once daily for seven days', 'armGroupLabels': ['Dexamethasone', 'Standard of care'], 'otherNames': ['Dexametasona kern pharma solution for injection 4 mg/ml']}

Primary Outcomes:
- {'measure': 'The primary trial outcome is the development of moderate-severe ARDS', 'description': 'Based on the Berlin criteria, moderate ARDS is defined by a PaO2/FiO2 ratio \\>100 mmHg and ≤200 mmHg. According to The American College of Chest Physicians patients with a PaO2/FiO2 ratio around 200 mmHg requiring supplemental oxygen in nasal cannula at 3 L/min (FiO2 0.30) for a SpO2 of 91-92%. The collected data as outcome measure will be general vital sign, Sequential Organ Failure Assessment (SOFA) score, the clinical status of the patient using the ordinal scale of the WHO, SpO2, partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio calculated from SpO2/FiO2, blood routine tests and chest radiography. Concomitant drugs and adverse event monitoring will be collected. Data will measure during admission. Participants will schedule for a follow-up visit on the 30 and 90th day to track their long-term prognosis, clinical status and sequelae.', 'timeFrame': '7 days'}

Please estimate the sample size based on the assumption: 
80% power, two-sided alpha = 0.05, potential loss to follow-up
Sample size
        We powered the study to assess whether the intervention would reduce the incidence of ARDS. Based on available evidence, we estimate a 30% risk of ARDS in the control group [2]. We are looking for an ARDS 10% absolute reduction in the intervention group. Assuming 80% power and two-sided alphaâ=â0.05, 226 participants would be needed to detect the resulting reduction of ARDS from 30% in the control group to 20% in the intervention group. We adopted a sample size of 252 (126 per group) to compensate for the potential loss to follow-up of some participants.