| disease_stage_preferred | | | |
| Acute/Recent onset | A short-term infection or disease characterized by a dramatic onset and rapid recovery. Primary infections fall under this category. | | |
| Chronic | A long-term infection or illness and partial remission. | | |
| Critical COVID-19 | Defined by the criteria for acute respiratory distress syndrome (ARDS), sepsis, septic shock, or other conditions that would normally require the provision of life-sustaining therapies such as mechanical ventilation (invasive or non-invasive) or vasopressor therapy. | | |
| Non-severe COVID-19 | Defined as absence of any criteria for severe or critical COVID-19. | | |
| Other | Any disease stage that cannot be classified under the selections above will be classified under "other." Household contacts will be recorded as "other". | | |
| Post | Recovery from an illness, including latent (potentially existing but not presently evident or realized) and remission (a period during which symptoms of disease disappear [complete remission]). Note that partial remission will be recorded as "chronic". | | |
| Severe COVID-19 | Defined by any of: Oxygen saturation < 90% on room air. Respiratory rate > 30 breaths/min in adults and children > 5 years old; >= 60 breaths/min in children < 2 months old; >= 50 in children 2–11 months old; and >= 40 in children 1–5 years old. Signs of severe respiratory distress (accessory muscle use, inability to complete full sentences, and, in children, very severe chest wall indrawing, grunting, central cyanosis, or presence of any other general danger signs). | | |
| Unknown | Used when the disease stage is not clearly specified or known. | | |