Clinical Course of COVID-19: presenting symptoms, how the illness progresses clinically, and why patients deteriorate

According to the Department of Health, the recognised symptoms of COVID-19 (coronavirus) currently include fever, shortness of breath, and flu-like symptoms such as coughing, sore throat and fatigue.

Others may include reduced sense of smell or taste, altered taste, gastrointestinal symptoms and cardiac presentations, including new onset myocarditis, pericarditis or atrial fibrillation.
Gastrointestinal symptoms comprised the chief complaint in 48.5% of patients, a paper published in The American Journal of Gastroenterology on 20 March found.

Patients with COVID-19 may appear to improve but can then experience a rapid deterioration later in the illness. Some patients spontaneously improve, and other patients deteriorate. The deterioration can be a few days, even a week later, rather than a stepwise deterioration from the time of presentation. That can make it tricky, just as patients appear to be improving clinically, they can deteriorate rapidly.

The below progression of symptoms, written by an Emergency Physician in New Orleans is likely to be an accurate representation of the clinical course of COVID-19 (it is consistent with data from Wuhan China):

  • Day 2–11 post-exposure (on average, day 5) – the patient develops onset of flu-like symptoms. These commonly include fever, headache, dry cough and muscle aches (mainly back pain), nausea without vomiting, abdominal discomfort with some diarrhoea, anorexia, reduction in smell and fatigue.
  • Day 5 – The patient is likely to develop increasing shortness of breath due to bilateral viral pneumonia.
  • Day 10 – A cytokine storm may occur in those with severe manifestations of SARS-CoV-2, leading to acute lung injury (previously known as acute respiratory disease syndrome [ARDS]) and multi-organ failure.
    • What that means is the capillary bed (where the oxygen gets into the blood) and the alveolar spaces (the tiny little sacks through which oxygen is exchanged) are damaged and inflamed. Their lungs become stiff and don’t exchange gas and they die a hypoxic (not enough oxygen) death

According to the above source, 81% of patients experience mild symptoms, 14% have a severe disease requiring hospitalisation, and 5% of patients become ‘critical’.

According to research in The Lancet, patients with COVID-19 who tend to fare worse include those who are older, and those who have underlying comorbidities such as hypertension and cardiovascular disease.

It is currently unclear whether patients who undergo that rapid deterioration are those who had a more severe illness to begin with, or whether people with mild illness are as likely to go downhill.

The minority of people who develop an acute lung injury and survive, or those who develop secondary bacterial pneumonia, may end up with permanent pulmonary fibrosis.

Remember though, the vast majority of patients with COVID-19 recover from the illness

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Dr Lachlan Soper