What is the Difference Between Flu and COVID-19?

From the Centers for Disease Control and Prevention (CDC)

Think it’s easy to tell the difference between symptoms of influenza (flu) and COVID-19? Think again. Both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms (asymptomatic) to severe symptoms. Common symptoms that COVID-19 and flu share include:

  • Fever or feeling feverish/having chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Vomiting and diarrhea
  • Change in or loss of taste or smell, although this is more frequent with COVID-19.

Flu and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus first identified in 2019, and flu is caused by infection with influenza viruses. Some differences to keep in mind include:

  • COVID-19 seems to spread more easily than flu. However, as more people become fully vaccinated against COVID‑19, the CDC says the spread of the virus that causes COVID‑19 should slow down.
  • Compared to flu, COVID-19 can cause more serious illnesses in some people.
  • COVID-19 can also take longer before people show symptoms and people can be contagious for longer.

Because some of the symptoms of flu, COVID-19, and other respiratory illnesses are similar, the difference between them cannot be made based on symptoms alone. The CDC says testing is needed to tell what the illness is and to confirm a diagnosis, especially since people can be infected with both flu and the virus that causes COVID-19 at the same time and have symptoms of both influenza and COVID-19.

To read more, visit the CDC’s page on Similarities and Differences between Flu and COVID-19, or its detailed pages on Flu Symptoms and COVID-19 Symptoms.

Be sure to also read our post Now is the Time to Catch Up on Immunizations highlighting August’s recognition as National Immunization Awareness Month.