Hyperbaric Oxygen Therapy Effect in COVID-19 RCT (HBOTCOVID19)

Inclusion Criteria: * Within 7 days of patient's need of oxygen supply * Positive SARS-CoV-2 RT-PCR * At least one risk factor for bad prognosis of COVID-19: Moderate-severe Asthma, Diabetes mellitus, Cardiac conditions (congestive heart failure, coronary disease, cardiomyopathy, pulmonary hypertension), severe obesity (BMI\>40), age\>65, immunodeficiency, chronic liver disease. * Respiratory insufficiency : Room Air SpO2 \<94% or PaO2/FiO2\<300mmHg * Age\>18 * Ability to sign an informed consent Exclusion Criteria: * HBOT contraindication: pneumothorax, pneumomediastinum, claustrophobia, ear/sinus disease which aren't allowed in HBOT, known chronic pulmonary disease: severe emphysema or known pulmonary bullae. * Pregnancy * Inability to sign an informed consent