The NIH definitions of severity are as follows: Mild illness: Patients who have any signs and symptoms of COVID-19 (eg, fever, cough, sore throat, malaise, headache, muscle pain) but without shortness of breath, dyspnea, hypoxemia, or abnormal chest imaging Moderate illness: Patients who have evidence of lower respiratory disease by clinical assessment or imaging, and an oxygen saturation (SpO2) ≥ 94% on room air at sea level Severe illness: Patients who have respiratory rate > 30 breaths per minute, SpO2 < 94% on room air at sea level (or, for patients with chronic hypoxemia, a > 3% decrease from baseline), ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) < 300 mmHg, or lung infiltrates > 50% Critical illness: Patients who have respiratory failure, septic shock, and / or multiple organ dysfunction The effectiveness of particular antiviral drugs and monoclonal antibodies against locally circulating variants is considered when making treatment decisions (see Open Data Portal: database of in vitro therapeutic activity against SARS-CoV-2 variants).