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Clinical presentation of COVID-19
What are the clinical presentation and natural history of COVID-19?
The spectrum of illness associated with COVID-19 is wide, ranging from asymptomatic infection to life-threatening respiratory failure. When symptoms are present, they typically arise three to five days after exposure. Most symptomatic infections are mild. Cough, myalgias, and headaches are the most commonly reported symptoms. Other features, including diarrhea, sore throat, and smell or taste abnormalities
Pneumonia, with fever, cough, dyspnea, and infiltrates on chest imaging, is the most frequent serious manifestation of infection. Progression from dyspnea to acute respiratory distress syndrome (ARDS) can be rapid; thus, the onset of dyspnea is generally an indication for hospital evaluation and management.
ARDS can be associated with an exuberant inflammatory response, which is characterized by fever, progressive hypoxia and/or hypotension, and markedly elevated inflammatory markers. Other complications of severe illness include thromboembolic events, acute cardiac injury, kidney injury, and inflammatory complications.
The time to recovery is highly variable and depends on age and pre-existing comorbidities in addition to illness severity. Individuals with mild infection are expected to recover relatively quickly (eg, within two weeks), whereas many individuals with severe disease have a longer time to recover (eg, two to three months). The most common persistent symptoms include fatigue, dyspnea, chest pain, cough, and cognitive deficits.
The overall case fatality rate in unvaccinated individuals is estimated to be between 0.15 and 1 percent, although it varies widely by age and other patient characteristics. While severe and fatal illnesses can occur in anyone, the risk rises with age and the presence of chronic illnesses, including cardiovascular disease, pulmonary disease, diabetes mellitus, kidney disease, and cancer.
What factors are associated with severe COVID-19?
Severe illness can occur in otherwise healthy individuals of any age, but it predominantly occurs in adults with advanced age and/or certain underlying medical comorbidities and among those who are not vaccinated.
| Symptoms that may be seen in patients with COVID-19 |
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Is COVID-19 caused by the Omicron variant less severe than infection caused other variants?
Early data suggest that COVID-19 caused by the Omicron variant is less severe than infection caused by prior variants. Some studies have shown a reduced risk of hospitalization, intensive care unit admission, and in-hospital mortality. The relative mildness of disease reported in these studies may reflect the younger age of individuals impacted at this stage of the surge or a higher proportion of reinfections. While illness due to the Omicron may be milder, the high volume of cases continues to lead to high hospitalization rates and may result in an excess burden on the health care system.
