Scientists identify order in which Covid-19 symptoms appear

  • Symptoms in Covid-19 differ from one patient to another
  • Scientists have, however, found that the order of Covid-19 symptoms differs from other diseases
  • Understanding this order can help speed up diagnosis and treatment

Since the start of the coronavirus pandemic, the list of potential signs and symptoms has become significantly longer.

As there are so many variables, it may be hard to tell whether a general symptom such as fever or coughing indicates that a person has Covid-19, or something else.

But according to scientists from USC Michelson Center, the order of the appearance of symptoms could help doctors diagnose Covid-19 more quickly.

Order of symptoms can help doctors plan treatment

Not only will the order of the symptoms help doctors diagnose Covid-19 at an earlier stage, but it will also give them a clearer understanding of which treatments to prioritise.

It also may help doctors rule out other illnesses, according to the study led by doctoral candidate Joseph Larsen and his colleagues, with faculty advisors Peter Kuhn and James Hicks, at the USC Michelson Center for Convergent Bioscience Convergent Science Institute in Cancer.

"This order is especially important to know when we have overlapping cycles of illnesses like the flu that coincide with infections of Covid-19," stated Kuhn, a USC professor of medicine, biomedical engineering, and aerospace and mechanical engineering, in a news release. "Doctors can determine what steps to take to care for the patient, and they may prevent the patient's condition from worsening."

"Given that there are now better approaches to treatments for Covid-19, identifying patients earlier could reduce hospitalisation time," said Larsen, the study's lead author.

"The order of the symptoms matters. Knowing that each illness progresses differently means that doctors can identify sooner whether someone likely has Covid-19, or another illness, which can help them make better treatment decisions," Larsen stated in the news release.

The scientific findings were published in the journal Frontiers in Public Health on 12 August 2020. 

Upper GI tract likely to be infected first

While fever and a dry cough are the key symptoms of Covid-19 – as with the two diseases SARS and MERS, which were also caused by coronaviruses – the timing of symptoms related to the gastrointestinal system seems to differ in Covid-19.

According to the researchers, the upper GI tract seems to be affected (nausea and vomiting) before the lower GI tract (diarrhoea) in Covid-19, unlike in MERS and SARS where it was the other way round. 

They determined the order of symptoms this spring from the rates of symptom incidence in more than 55 000 confirmed coronavirus cases in China (all of which were collected between 16 February and 24 February 2020, by the World Health Organization). They also studied a dataset of nearly 1 100 cases (collected between 11 December 2019 and 24 January 2020, by the China Medical Treatment Expert Group via the National Health Commission of China.)

The researchers then compared the order of Covid-19 symptoms to those of influenza by examining data from 2 470 cases in North America, Europe and the Southern Hemisphere (reported to health authorities from 1994 to 1998).

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Image credit: Polina Tankilevitch from Pexels

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