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Understanding the Differences and Similarities Between the Flu and COVID-19

Differentiating between influenza (flu) and COVID-19 can be tricky. That’s because flu symptoms are very similar to COVID-19 symptoms.1

With flu season quickly approaching, it is likely that both viruses will spread this fall and winter. In order to avoid a potential “twindemic” this year—an influenza epidemic coinciding with the COVID-19 pandemic—it’s essential to know how they are different from one another so that you can take every precaution to protect yourself and others.

Continue reading to learn the similarities and differences between the flu and COVID-19.

What are the similarities?

Influenza and COVID-19 are both contagious respiratory illnesses that share similar symptoms and are spread in similar ways.1

Similar symptoms

The flu and COVID-19 share many similar characteristics and symptoms, making it hard to tell them apart. Those symptoms include:

  • Fever
  • Body aches
  • Cough
  • Sore throat
  • Shortness of breath/difficulty breathing
  • Fatigue
  • Headaches
  • Runny nose
  • Vomiting
  • Diarrhea

They spread in similar ways

Both the flu and COVID-19 are transmitted through respiratory droplets in the air that come from our mouths when we cough and sneeze. They can also be spread by talking, laughing, and eating.2

Both the flu and COVID-19 may be spread by someone before showing any symptoms, mild symptoms, or are asymptomatic (someone who never develops symptoms). 1

Unlike the flu, however, COVID-19 may be spread by touching an object or surface that has the virus on it, then touching your mouth, nose, or eyes.1

COVID-19 is thought to be more contagious in certain age groups and populations and has been shown to be more of a super-spreader than the flu.1 Typically, patients with the flu are contagious for about one day prior to showing symptoms and are most contagious the first 3-4 days after experiencing symptoms.

With COVID-19, patients can be contagious two days before showing signs of the virus and up to 10 days after symptoms have appeared.

What are the differences?

While they are similar in many ways, influenza and COVID-19 are caused by two completely different viruses.1 There are also a few tell-tale signs and symptoms to be on the lookout for in patients with COVID-19.

Different symptoms3

  • Loss of taste and smell: While not everyone will experience a loss of taste and smell, this symptom is specific to COVID-19 and is not seen in flu cases. Loss of taste and smell may occur within a few days of contracting the virus or up to two weeks later.
  • Symptoms may linger: With COVID-19, symptoms tend to last longer than the flu and may be more severe—particularly shortness of breath. Lingering symptoms may include loss of taste and smell, cough, and shortness of breath and may last for several weeks, sometimes months and are more common in older adults or those with preexisting conditions.4
  • Red, swollen eyes: Some COVID-19 patients have experienced red, itchy, and swollen eyes that resemble conjunctivitis (or pink eye).5
  • Skin rashes: Mostly seen in younger patients, COVID-related skin rashes range from hives and little red bumps to sores on the toes, what some experts refer to as ‘COVID toes.’ 6

What kinds of complications may occur?

Both the flu and COVID-19 can result in complications1 for high-risk individuals, some of which can be life-threatening (pneumonia and respiratory failure), however, additional complications exist with COVID-19:

  • Blood clots in the veins and arteries of the lungs, heart, legs, or brain have been reported in adults who develop a severe case of COVID-19.1
  • Children who develop COVID-19 are at a higher risk of developing multisystem inflammatory syndrome, or MIS-C, a rare but severe complication of COVID-19.7

How can they be treated?

If you are experiencing any of the above symptoms, contact your doctor and get tested for both the flu and COVID-19 as soon as possible. The flu can be treated with an antiviral drug which helps to reduce the severity of symptoms.8

In mild cases of COVID-19, plenty of rest and fluids are recommended. Isolate yourself from your family, and continue to monitor your symptoms. While most people can recover at home, you should seek emergency medical treatment if you have trouble breathing, chest pressure, new confusion, an inability to wake or stay awake, or bluish lips or face.9

How can they be prevented?

Just as there are similarities between the flu and COVID-19, they both can be prevented in much the same way: avoiding large crowds, wearing a mask, washing your hands often, and limiting contact with others if you feel sick.10  Getting a flu shot is also highly recommended. It’s the best way to prevent getting the flu.11

While it may be too soon to know whether a “twindemic” lays ahead, we can take the necessary precautions to reduce our chances of getting sick.


1: Similarities and Differences Between Flu and COVID-19. Available here: Accessed September 27, 2020.

2. How COVID-19 Spreads. Available here: Accessed September 27, 2020.

3. Symptoms of Coronavirus. Available here: Accessed September 27, 2020.

4. Ringer, Janelle. Is it Flu or COVID-19? Here’s What Doctors Say. Loma Linda University Health: September 2, 2020. Available here:

5. Boyd, Kierstan. Is It COVID-19 or Allergies? American Academy of Ophthalmology. April 14, 2020. Available here:

6. American Academy of Dermatology Association. COVID Toes, Rashes: How the Coronavirus Can Affect Your Skin. Available here: Accessed September 27, 2020.

7. Ahmed, Mubbasheer; Advani, Shailesh; Moreira, Axel; Zoretic, Sarah; Martinez, John; Chorath, Kevin; et al. Multisystem Inflammatory Syndrome in Children: A Systematic Review. September 4, 2020: The Lancet. Available here:

8. What You Should Know About Flu Antiviral Drugs. Available here: Accessed September 27, 2020.

9. Coronavirus: What To Do If You Are Sick. Available here: Accessed September 27, 2020.

10. Maragakis, Lisa, M.D. Coronavirus Disease 2019 vs. the Flu. Johns Hopkins Medicine. Available here:

11. Prevent Seasonal Flu. Available here: Accessed September 28, 2020.