covid symptoms

COVID-19 Vs. Flu: Knowing the Difference in Symptoms

Here's a look at the difference between coronavirus and flu symptoms, according to the Centers for Disease Control and Prevention

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As the coronavirus pandemic collides with flu season and health officials brace for the possibility of what's being called a "twindemic," many might be wondering if their symptoms are a sign of the flu or COVID-19.

According to the Illinois Department of Public Health, there have already been reports of "coinfections" of both coronavirus and the flu in the state.

IDPH Director Dr. Ngozi Ezike didn't provide a number of affected patients, but noted Monday "we're not anywhere near the peak of flu season."

Coinfections have been reported in other parts of the country as well, such as El Paso, Texas, which emerged as a COVID-19 hotspot in the previous months, CNBC reported.

Here's a look at the difference between coronavirus and flu symptoms, according to the Centers for Disease Control and Prevention:


According to the CDC, "both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms (asymptomatic) to severe symptoms."

Common symptoms reported for both illnesses include:

  • Fever or feeling feverish/chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Some people may have vomiting and diarrhea, though this is more common in children than adults



Flu viruses can cause mild to severe illness, including common signs and symptoms listed above.


COVID-19 seems to cause more serious illnesses in some people. Other signs and symptoms of COVID-19, different from flu, may include change in or loss of taste or smell.

Another difference could be when symptoms arrive.

Both COVID-19 and flu can take a day or more for symptoms to appear following infection, the CDC reports. But for coronavirus patients, it could take longer for symptoms to arrive.

Flu patients typically develop symptoms within four days, while coronavirus patients could develop them as late as two weeks after infection.

Someone with the coronavirus could also be contagious for longer than someone with the flu. Most people with flu are contagious roughly one day before they begin experiencing symptoms.

For COVID-19, the length of spread is still being studied, but the CDC reports "it’s possible for people to spread the virus for about two days before experiencing signs or symptoms." COVID-19 patients could also remain contagious for at least 10 days after signs or symptoms first appeared.

"If someone is asymptomatic or their symptoms go away, it’s possible to remain contagious for at least 10 days after testing positive for COVID-19," the CDC states.

COVID-19 and flu spread in similar ways, but coronavirus is more contagious among certain populations and age groups, the CDC reports, adding that coronavirus has been linked to more "superspreading events" than flu.

"This means the virus that causes COVID-19 can quickly and easily spread to a lot of people and result in continuous spreading among people as time progresses," according to the CDC.

As part of National Influenza Vaccination Week, which started Monday, Ezike encouraged everyone six months and older to receive the seasonal flu vaccine to avoid coinfection.

 “Not only could being infected with both a flu virus and the virus that causes COVID-19 result in severe health complications for individuals, it also places a tremendous burden on our health care system and health care workers who are being stretched due to the increase in COVID-19 cases," Dr. Ezike said in a news release.

Still, state health officials are optimistic they'll see lower flu numbers this year, because mitigation strategies to prevent COVID-19, such as wearing facial coverings, are also effective at reducing the spread of the flu.

"We're hoping that benefit of the mask will definitely extend to the flu hospitalizations as well," Ezike said. "So keep wearing that mask. We're accomplishing many good things in terms of cutting down infectious trends."

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