Course and Progression of COVID-19

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According to the CDC, the following signs and symptoms are associated with COVID-19 at time of illness onset: fever, constant or intermittent (83-99%), cough (59%–82%), fatigue (44-70%), anorexia (48-80%), shortness of breath (31-40%), sputum production (28-33%), and myalgias (11-35%).  The CDC also noted that while fever was present in only 44% of patients at the time of hospital admission, 89% of patients became febrile during their admission.  Other possible symptoms include sore throat, headache, productive cough, nausea, and diarrhea, but these occurred in <10% of patients.

The clinical course and progression of COVID-19 is variable.  The CDC offers Interim Clinical Guidance for Management of Patients with Confirmed Coronavirus Disease (COVID-19).  The illness severity may worsen over the course of the disease.  Illness severity may range from mild to critical.  Individuals with mild illness, which comprises as many as 81% of cases of COVID-19, may not require hospitalization, and some may be asymptomaticMild to moderate disease is classified as ranging from asymptomatic to presenting with mild pneumonia.  These individuals do not demonstrate dyspnea or hypoxia.

Severe disease is defined as COVID-19 positive patients demonstrating dyspnea, hypoxia, or >50% lung involvement on imaging. The most common radiologic abnormality is bilateral ground glass opacities. About 14% of patients with COVID-19 develop severe disease.  About 5% of patients develop critical disease.  Critical disease is defined as those patients with COVID-19 who demonstrate associated respiratory failure, shock, or multiorgan system dysfunction. 

Some patients with severe or critical disease present at the critical stage, while others present with mild disease and progress to severe or critical disease.  It is difficult to determine which patients will progress to develop severe or critical disease, but age and underlying medical conditions are risk factors. The provider must also consider the time from symptom onset to patient presentation when determining rate of disease progression. The CDC reports that the medium time to dyspnea ranged from 5-8 days in those patients who developed severe disease.  For those that developed critical disease, the medium time to development of ARDS ranged from 8-12 days.  

Inpatient management of patients with severe and critical disease is largely supportive.  The most common complications of critical disease include ARDS, acute kidney injury, septic shock, cardiomyopathy, dysrhythmias, and thromboemboli. Patients requiring prolonged mechanical ventilation are also at risk for critical illness polyneuropathy/myopathy. Treatments for COVID are discussed in full here. Age and underlying medical conditions are key in predicting outcomes of patients with COVID-19.  The most recent data provided by the CDC was as of April 3, 2020.  The overall case fatality rate has been reported as 2.3%.  The case fatality rate for those requiring ICU admission is 49%. As per data provided by the CDC, among U.S. COVID-19 cases with a known disposition, the proportion of persons who were hospitalized was 19%.  The proportion admitted to the intensive care unit (ICU) was 6%.   The elderly are at greatest risk of dying from COVID-19.  Early data from the US as reported by the CDC indicates the case fatality is highest in persons aged ≥85 years (10%–27%), followed by 3%–11% for ages 65–84 years, 1%–3% for ages 55–64 years, and <1% for ages 0–54 years. Individuals with heart disease, lung disease, cancer, liver disease, kidney disease, diabetes and those with immunocompromised states are also at higher risk to develop serious illness.

Julie Grishaw, ACNP

Senior Editor, McGraw-Hill Education