New research reveals the most common pattern of COVID-19 symptoms, which could be extremely important come fall and winter when flu season begins to peak.
LOS ANGELES — COVID-19 patients can have symptoms that are very similar to other viral illnesses. This makes it difficult to know when to seek medical care. It also poses a diagnostic challenge for doctors. As cold and flu season approaches, it’s even more important to be able to differentiate COVID-19 from other respiratory diseases. A new study by scientists at the University of Southern California offers valuable guidance when it comes to the onset of coronavirus symptoms.
The study, published in Frontiers in Public Health, finds that a distinguishing feature of COVID-19 is the order in which symptoms first appear. Typically, patients will experience fever, cough, muscle pain and then nausea, and/or vomiting, and diarrhea.
To reach this conclusion, the USC researchers studied the rates of symptom incidence in two datasets of COVID-19 patients. The main dataset includes more than 55,000 confirmed coronavirus cases in China collected between February 16 and February 24, 2020 by the World Health Organization. The team also looked at a smaller dataset of about 1,100 cases from December and January in order to confirm their findings.”
Using these data, the scientists created a model that predicts the probability of COVID-19 symptoms occurring in a specific order. They then compared their results to the likely order of symptoms in patients with other respiratory diseases. The other diseases included in the study are influenza, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). MERS and SARS are both closely related to the coronavirus that causes COVID-19.
“The order of the symptoms matter. 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,” explains Joseph Larsen, the study’s lead author, in a statement.
How coronavirus symptoms differ from flu symptoms
The study finds that fever and cough are frequently associated with all four diseases studied. For influenza, the first symptom is more likely to be cough. In the three coronavirus infections, the most common initial symptom is fever.
Scientists report that it is the timing of gastrointestinal symptoms that sets COVID-19 patients apart from MERS and SARS patients. In COVID-19 patients, upper tract GI symptoms like nausea and vomiting seem to appear before lower GI tract symptoms like diarrhea. This is the reverse for patients with MERS and SARS.
“This order is especially important to know when we have overlapping cycles of illnesses like the flu that coincide with infections of COVID-19,” says study co-author Peter Kuhn. “Doctors can determine what steps to take to care for the patient, and they may prevent the patient’s condition from worsening.”
Identifying symptoms earlier can help slow spread of virus
According to the authors, early identification of whether someone likely has COVID-19 or another illness is also important. That’s because of the great need to stop the spread of coronavirus. Compared to influenza, COVID-19 is two to three times more transmissible.
However, the authors caution that the identification of symptom order should not be used in place of testing. Instead, it should be taken as a possible sign to get tested.
“Given that there are now better approaches to treatments for COVID-19, identifying patients earlier could reduce hospitalization time,” concludes Larsen.