Table 1.
| Feature | SARS | MERS | COVID-19 |
|---|---|---|---|
| CLINICAL SIGN OR SYMPTOM | |||
| Fever or chills | Yes | Yes | Yes |
| Dyspnea | Yes | Yes | |
| Malaise | Yes | Yes | |
| Myalgia | Yes | Yes | |
| Headache | Yes | Yes | Yes |
| Cough | Dry | Dry or productive | Dry (productive w/progressive illness) |
| Diarrhea | Yes | Yes | +/- |
| Nausea or vomiting | Yes | Yes | Less common |
| Sore throat | Yes | Uncommon | Less common/but possible |
| Arthralgia | Yes | Uncommon | Less common/but possible |
| IMAGING FINDINGS | |||
| Acute phase | |||
| Initial imaging | |||
| Normal | 15–20% of patients | 17% of patients | 15–20% of patients |
| Abnormalities | |||
| Common | Peripheral multifocal airspace opacities (GGO, consolidation or both) on chest XRay lung and CT scans | Diffuse findings similar to SARS | Diffuse findings similar to SARS and MERS; may be, more diffuse early, or more rapidly progressive. B/L involvement to be expected |
| Rare | Pneumothorax | Pneumothorax | Pneumothorax |
| Not seen | Cavitation, lymphadenopathy | Cavitation, lymphadenopathy | Cavitation, lymphadenopathy |
| Appearance as | Unilateral, focal (50%); Multifocal (40%); diffuse (10%) Bilateral, multifocal CXR | Bilateral, multifocal basal airspace on or CT (80%), isolated unilateral (20%) | Bilateral, multifocal, as well as basal airspace are common findings. Of note, a </=15% may present with normal CXR |
| Follow-up imaging appearance | Unilateral, focal (25%); Progressive (most common, can be unilateral and multi-focal or bilateral with multi-focal consolidation) | Extensive into upper lobes or perihilar areas, pleural effusion (33%), interlobular septal thickening (26%). | Persistent or progressive airspace opacities |
| Indications of poor prognosis | Bilateral (like ARDS), four or more lung zones,progressive involvement after 12 d | Greater involvement of the lungs, pleural effusion, pneumothorax | Consolidation vs ground glass opacities (GGO) |
| SARS | MERS | COVID-19 | |
| Chronic phase | Data still being reviewed | ||
| Transient reticular opacities (e) | Yes | Yes | |
| Air trapping | Common (usually persistent) | ||
| Fibrosis | Rare | One-third of patients | Data still being reviewed |
Acronyms: GGO = ground-glass opacity, ARDS = acute respiratory distress syndrome. aOver a period of weeks or months.