Coronavirus or the Flu

Updated Sept. 18, 2020

The novel coronavirus — severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) —draws comparisons to influenza, the seasonal flu.

Reports of SARS-CoV-2 and COVID-19, the disease it causes, began in China in late December 2019 — the middle of flu season.

COVID-19 and the flu cause similar respiratory symptoms, but the two have many differences.

Similarities Between COVID-19 and the Flu

Both the flu and COVID-19 are respiratory diseases, but they come from different viruses. Novel coronavirus SARS-CoV-2 causes COVID-19, while influenza viruses cause the flu. But they do share several similarities.

How the flu and COVID-19 spread

Both the flu and COVID-19 can spread from person to person with close contact. If an infected person coughs, sneezes, or talks, they release respiratory droplets that can land in another person’s nose, eyes, or mouth.

The flu also can spread if uninfected people touch a surface that contains the virus and then touch their nose, mouth, or eyes. COVID-19 can spread in a similar way, although it is more commonly spread through respiratory droplet.

You do not need to be symptomatic to spread COVID-19 or the flu. Both can be spread by people who are not yet showing symptoms.

Groups at risk

Older adults, people with underlying health conditions (such as lung disease, heart disease, and diabetes), pregnant women, and children with certain medical conditions are at higher risk for severe illness from both COVID-19 and the flu.

Children without underlying health conditions are more at risk of severe illness from the flu than from COVID-19. COVID-19 symptoms in children are generally less severe, although some children have experienced a related serious inflammatory condition.

Flu symptoms vs. COVID-19 symptoms

Both the flu and COVID-19 cause similar symptoms, ranging from no symptoms at all to severe. In the most severe cases, both can cause serious illness or death.

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Differences Between COVID-19 and the Flu

The flu and COVID-19 do share similarities. However, they are different diseases and it is important to know the distinctions.

Tens of millions of people have been infected worldwide with the coronavirus since late 2019, according to the World Health Organization. The flu is much more common on an annual basis. The Centers for Disease Control and Prevention (CDC) estimates the flu affects between 9 million and 45 million people each year in the United States alone.

However, COVID-19 appears to be deadlier. Hundreds of thousands of people have died worldwide from COVID-19 since late 2019, according to the WHO. It also reports between 290,000 and 650,000 people worldwide die each year because of severe flu-related respiratory problems.

COVID-19’s death rate is changing, but it remains higher than the flu, which has a yearly fatality rate of around 0.1%

Other key differences between the two diseases include:

Contagiousness of the flu and COVID-19

It’s possible to spread both the flu and COVID-19 before showing any symptoms (that means you’re asymptomatic). However, the length of time you can spread the diseases differs:

  • With the flu, older children and adults are usually most contagious for the first 3 or 4 days of their illness. Many can be contagious for up to a week, and infants and young children can be contagious even longer.
  • Scientists are still studying how long someone can spread COVID-19. It’s possible to remain contagious for at least 10 days after symptoms appear, but it may be even longer. Even if you were asymptomatic or your symptoms went away, it’s possible to be contagious for 10 days or longer after testing positive for COVID-19.

Testing for the flu and COVID-19

Only lab tests can definitively diagnose COVID-19. Several different tests can diagnose the flu, and those tests are more widely available.

Treatment for the flu and COVID-19

If you have the flu, prescription antiviral medicines can help treat your illness, if taken early. They can help ease your symptoms, shorten your illness, and lessen your risk for complications. No specific medicine currently exists for COVID-19, though several clinical trials are underway. Currently, treatment is focused around supportive care and additional oxygen when needed.

Coronavirus and Flu Symptoms

Symptoms for both COVID-19 and the flu can range from no symptoms at all to severe and even life-threatening.

The most common symptoms of COVID-19 include fever, cough, and shortness of breath. Symptoms generally appear anywhere between 2 and 14 days after exposure. The CDC reports most symptoms appear 5 days after infection, but that timeframe varies. Flu symptoms can come on suddenly, usually between 1 and 4 days after exposure.

Both the flu and COVID-19 can cause serious health complications like pneumonia, respiratory failure, organ failure, heart damage, and more.

Coronavirus and Flu Diagnosis

Only lab tests can definitively diagnose COVID-19 at this time. If you are showing symptoms of COVID-19, or you think you have been in contact with someone who has COVID-19, call your health care provider.

The current tests for a COVID-19 infection are known as viral tests or diagnostic tests. According to the Food and Drug Administration, they include molecular tests, which look for the virus’ genetic markers, and antigen tests, which can detect proteins on the virus’ surface. At UPMC, we use molecular tests. Specimens can be collected from multiple sites in your nasal cavity or mouth.

Several different tests can diagnose the flu, and those tests are more widely available.


Can I Prevent Coronavirus or the Flu?

The CDC recommends that everyone older than 6 months get an annual flu shot, which can help prevent you from getting infected with the flu. There is no vaccination available yet for COVID-19.

Specific methods to prevent the spread of COVID-19 include:

  • FacemasksFollow the CDC’s recommendations for wearing facemasks. The CDC recommends wearing a facemask when out in public to prevent spread of the coronavirus. Pennsylvania currently requires the use of facemasks in public settings for everyone over the age of 2. Children under age 2 should not wear facemasks. You should not purchase masks or respirators that are meant for health care workers. Learn more about facemask use, including how to craft your own at home.
  • Social distancing: When out in public, maintain at least 6 feet of distance from people who are not members of your household.

There are also prevention methods you can use for both the coronavirus and the flu. These steps can help protect you from getting infected by the flu or COVID-19 and help prevent their spread:

  • Avoid contact with people who are infected
  • Stay home if you’re sick
  • Cover your mouth and nose when you sneeze or cough
  • Wash your hands with soap and water or an alcohol-based hand sanitizer. Wash for at least 20 seconds — especially after coughing and sneezing, using the bathroom, and before eating
  • Avoid touching your nose, eyes, or mouth
  • Disinfect commonly touched surfaces, such as tables and counters, at work, home, and school
  • Wash your hands after touching commonly used surfaces

For more information on the coronavirus, visit


Anthony S. Fauci, M.D.; H. Clifford Lane, M.D.; Robert R. Redfield, M.D. Seasonal Influenza (Flu) . Centers for Disease Control and Prevention.

About Infectious Diseases

If you have a disease caused by bacteria, fungi, parasite, or virus, the UPMC Center for Care of Infectious Diseases can help. We have specialty units for prevention and treatment of HIV-AIDs, postsurgical and transplant infections, and illnesses caused by international travel. Our faculty research infectious diseases and participate in clinical trials to learn more and develop better treatment and prevention methods.