What Do I Have? Flu or COVID-19?

Published on Oct 11, 2021 | 2:58 PM

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Not sure if you've got a cold, the flu or COVID-19? The symptoms are so closely related it's got many people questioning what they really have. To make things simple, here is a compiled list from our providers with guidance from the CDC to help you determine the similarities and differences between the flu and COVID-19.

Similarities & Differences: Influenza VS Covid-19

Here we’ve compiled all the frequently asked questions, as well as the facts regarding the similarities and differences between the flu and COVID-19, according to the Centers for Disease Control and Prevention (CDC).



  • The annual flu (influenza) and COVID-19 are both contagious upper respiratory illnesses that are transmitted through contact with a person and an infected person’s particles that contain the virus.

  • Both illnesses are thought to be transmitted between people via an infected person’s particles spread by coughing, sneezing or talking. 

  • They are both mostly spread through inhalation, but a person can also be infected by touching something with virus particles on it, and then touching their own eyes, nose, or mouth.

  • Poor ventilation of indoor settings may cause particles from both illnesses to spread farther and cause infections.

  • For both COVID-19 and the influenza viruses, it’s possible to spread the virus before experiencing symptoms.

  • Both illnesses may increase the risk for severe illness and complications in high-risk individuals, including pregnant women, older adults and infants, children, and adults with underlying conditions that make them more susceptible to infection.

  • COVID-19 and the flu share common symptoms. These include sore throat, runny nose, sinus congestion, taste and smell loss or changes, diarrhea, vomiting, headache, cough, fatigue, fever, chills, difficulty breathing, body aches, muscle pain, and shortness of breath.

  • Complications associated with both flu and COVID-19 include cardiac injury; multiple organ failure; inflammation of the heart, brain, or muscle tissue; and fluid in the lungs.

  • The CDC recommends washing hands often; not touching eyes, nose, or mouth; and covering coughs and sneezes for both illnesses.

*While symptoms alone cannot help you fully determine if you have COVID or the flu, here is a chart to help you understand the similarities and differences between Influenza and COVID-19 symptoms.



As per our Call-On-Doc Guide to the Flu, there are a handful of qualities concerning the flu that set it apart from other respiratory illnesses. These can include: 

  • A person with the flu can experience symptom onset one to four days after infection.

  • Those infected with influenza are most contagious in the first three to four days, but many people may be contagious for seven days.

  • The flu has been traced to Influenza A or Influenza B virus.

  • Influenza mainly affects any age of persons with chronic medical conditions, pregnant women, and children younger than five. 

  • Most who get the flu will take between three days and two weeks to recover on their own.

  • Some will experience secondary bacterial infections.


As per our CallonDoc Guide to Covid-19, SARS-Cov-2 easily gets confused with influenza, as it affects the same parts of the body as the other virus, but there are symptoms and signs that can differentiate the two including: 

  • People with COVID-19 may show symptoms 2 to 14 days after infection.

  • COVID has been traced to the SARS-CoV-2 virus.

  • COVID has more serious complications for older adults and those with heart/lung disease or diabetes.

  • Children are less likely to get COVID.

  • COVID has been reported to produce more congestion or runny noses, loss of taste/smell, and shortness of breath/difficulty breathing.

  • In addition to experiencing symptoms common with the flu, people who have had the virus may experience post-COVID conditions, which are symptoms that may last for weeks, months, or years after the initial infection.

When should I go to the hospital?

Since COVID, Influenza, and other respiratory illnesses are similar, determining the cause of illness cannot be based on symptoms alone-testing must be done.

When to seek emergency medical condition:

  • Trouble breathing

  • Pain or pressure in your chest

  • New confusion

  • The inability to wake/stay awake

  • Pale, gray,  and/or blue-colored skin, lips, or nail beds


Both the flu and Covid can be aggressive in terms of spread, both infecting people through the respiratory droplets we spray through coughing, sneezing, and speaking. When you contract either virus, quarantine is one of the best ways to keep others safe, meaning: 

  • Quarantine when you might have been exposed to the virus. 

  • The CDC recommends close contact with someone within six feet for a total of 15 minutes or more with someone who has COVID unless you have been fully vaccinated. 

  • People do not need to quarantine after contact if they’ve had COVID-19 vaccines and are fully vaccinated and not showing symptoms of COVID. 

  • The CDC now recommends getting tested at least five days after the last close contact with an infected person.

  • The CDC also now recommends that a well-fitting mask should be worn for 10 full days at home or in public, with previous recommendations being 14 days following exposure or until they receive a negative test. 


Isolate when you have been infected with the virus or have tested positive.

  • Isolation means to stay at home for at least five days.

  • The CDC recommends wearing a mask when around others in the home.

  • Isolation can be ended after five days when symptoms improve and you are fever-free for 24 hours with no medication use.

  • The CDC recommends that those with weakened immune systems or who experienced severe symptoms from the COVID-19 illness isolate for at least 10 days and consult their doctor before ending isolation.

  • People in isolation should stay home and separate from others within the home.

Have questions about the COVID-19 pandemic, or COVID and flu shots? Call on Doc is available around the clock from the comfort of your own home and can treat both COVID-19 and the flu. Get started here.

Get Flu Treatment Online

Get Covid Treatment Online


  • The Centers for Disease Control and Prevention (CDC)

  • The World Health Organization (WHO)

  • The American Academy of Family Physicians (AAFP)

  • The Food and Drug Administration (FDA)

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Wayne Hahne,

English graduate and Call-On-Doc’s medical resource guide, Wayne C. Hahne is an experienced and passionate medical education content expert. Through diligent research, provider interviews and utilizing the industry's leading resources for wellness information, it is Mr. Hahne’s personal mission to educate the general public on medical conditions with in-depth and easy-to-understand written guides.

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