When flu season collides with an expected second wave of COVID-19 this fall and winter, doctors will show particular interest in the order of a patient’s symptoms after a new study at the University of Southern California identified key differences in the respiratory diseases.

The researchers found fever is the most likely first symptom of COVID-19. When you get the flu, a cough is the most likely first symptom.

The complete order of COVID-19 symptoms, as they appear in most cases, according to the study (the flu can produce similar symptoms, but not in the same order):

  • Fever.
  • Cough.
  • Muscle pain.
  • Nausea or vomiting.
  • Diarrhea.

The study, published Aug. 13 in the Frontiers of Public Science, used data from 55,000 confirmed coronavirus cases in China collected from Feb. 16-24 by the World Health Organization, supplemented by about 1,100 additional cases from December and January. They also reviewed 2,470 reported cases of flu in North America, Europe and the Southern Hemisphere from 1994 to 1998.

COVID-19 symptoms tracked similarly to two related coronaviruses, MERS (Middle East Respiratory Syndrome) and SARS (Severe Acute Respiratory Syndrome). The first two symptoms of the three coronaviruses are fever and cough. Unlike SARS and MERS, however, COVID-19 tends to produce nausea and vomiting before diarrhea.

The 2003 SARS epidemic in China infected more than 8,000 people, causing 774 deaths. No SARS cases have been reported since 2004. MERS emerged in Saudi Arabia in 2012 with symptoms similar to SARS. It has since spread to other countries, including the United States.

SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), was first detected in December in Wuhan, the capital city of Hubei Province in central China.

The most elusive group in the study of COVID-19 remains those who test positive for the disease despite not showing any common symptoms.

“We still do not know the genetic predisposition of who develops little or no symptoms but can still spread the virus,” says Dr. Faiqa Cheema, a Hartford HealthCare infectious disease specialist, “and if age, gender and race has any role to play. Great questions for current scientific research.”

Not feeling well? Call your healthcare provider for guidance and try to avoid going directly to an emergency department or urgent care center, as this could increase the chances of the disease spreading.

Click here to schedule a virtual visit with a Hartford HealthCare-GoHealth Urgent Care provider.

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