COVID-19 vs. the Flu

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Influenza (the flu) and COVID-19, the illness caused by the pandemic coronavirus, are both contagious respiratory illnesses, meaning they affect your lungs and breathing, and can be spread to others. Although the symptoms of COVID-19 and the flu can look similar, the two illnesses are caused by different viruses.

Lisa Maragakis, M.D., M.P.H., senior director of infection prevention at Johns Hopkins, explains how the flu and COVID-19 are similar and how they are different.

Similarities: COVID-19 and the Flu

Symptoms

  • Both illnesses can cause fever, cough, body aches, and sometimes vomiting and diarrhea (especially in children). Learn more about COVID-19 symptoms.
  • Both can result in pneumonia.
  • Both flu and COVID-19 can be asymptomatic, mild, severe or even fatal.

How It Spreads

  • Both the flu and COVID-19 spread in similar ways. Droplets or smaller virus particles from a sick person can transmit the virus to other people nearby. The smallest particles may linger in the air, and another person can inhale them and become infected.
  • Or, people can touch a surface with viruses on it, and then transfer the germs to themselves by touching their face. 
  • People infected with the coronavirus or the flu may not realize they are sick for several days, and during that time can unknowingly spread the disease to others before they even feel sick.

Prevention

In most cases, serious disease and death due to COVID-19 or the flu can be prevented by vaccines. In addition, mask-wearing, frequent and thorough hand washing, coughing into the crook of your elbow, staying home when sick and limiting contact with people who are infected are effective safety precautions. Physical distancing limits the spread of COVID-19 and flu in communities.

Differences: COVID-19 and the Flu

Cause

COVID-19: Caused by the 2019 coronavirus, also known as SARS-CoV-2. There are different SARS-CoV-2 that have some differences in how severe or transmissible they are.

Flu: Caused by the influenza virus.  There are two main types of influenza virus called influenza A and influenza B. Different strains of influenza A and influenza B emerge and circulate each year.

Symptoms

COVID-19: Many people infected with the coronavirus do not feel sick or have only mild symptoms, but they can still transmit the coronavirus to other people. Review the full list of symptoms.

COVID-19 can sometimes cause a person to suddenly lose their sense of smell (anosmia) or taste (ageusia). This rarely occurs with flu, but it can occur with certain strains of the virus.

Flu: Flu does not typically affect a person’s sense of smell or taste, but otherwise has many symptoms similar to COVID-19 Rarely, as during the 1918 flu pandemic, a certain influenza strain does cause many people to lose their sense of taste or smell.

Treatment

While different treatments may be used for COVID-19 and the flu, both are treated by addressing symptoms, such as reducing fever. Severe cases may require hospitalization and very ill patients may need a ventilator — a machine that helps them breathe. For some patients, medications may help lessen the symptoms and shorten the duration of COVID-19 or flu.

COVID-19: Antiviral medications and other therapies are being tested to see if they can effectively address symptoms and shorten the duration of the illness.

Monoclonal antibodies are one such treatment, but need to be initiated early in the course of COVID-19. Contact your doctor as soon as possible after a positive COVID-19 diagnosis to see if you are eligible for monoclonal antibody treatment.

Currently, effective treatments are only available in an intravenous form, so they are not prescribed to patients outside of a healthcare setting.

Flu: Oral antiviral medications can address symptoms and sometimes shorten the duration of the illness. Because they are given by mouth, these antiviral therapies can be prescribed for patients who are not hospitalized as well as for those in the hospital.

Vaccine

COVID-19:Three types of COVID-19 vaccines have been approved or authorized for emergency use among specific age groups by the U.S. Food and Drug Administration (FDA). Johns Hopkins Medicine views all FDA approved or authorized COVID-19 vaccines as highly effective at preventing serious disease, hospitalization, and death from COVID-19. 

Learn more about coronavirus vaccine safety and what you need to know about the COVID vaccines.

Flu: A vaccine is available and effective in preventing some of the most dangerous types or to reduce the severity or duration of the flu. The flu vaccine is reformulated every year in anticipation of the influenza strains that are expected to circulate. It is very important to get vaccinated for the flu this year.

Complications

COVID-19: The development of complications, including long-term damage to the lungsheartkidneysbrain and other organs and a variety of long-lasting symptoms, is possible after a case of COVID-19.

Flu: Influenza complications can include inflammation of the heart (myocarditis), brain (encephalitis) or muscles (myositis, rhabdomyolysis), and multi-organ failure. Secondary bacterial infections, particularly pneumonia, can occur following a bout of influenza infection.

Infections

COVID-19: The first cases appeared in China in late 2019, and the first confirmed case in the United States appeared in January 2020.

Current COVID-19 infections*

Flu: The World Health Organization estimates that 1 billion people worldwide get the flu every year.

Cold and Flu Season Precautions: What to Do

  1. Get vaccinated for coronavirus. Three types of COVID-19 vaccines have been approved or authorized for emergency use among specific age groups by the U.S. Food and Drug Administration (FDA). Johns Hopkins Medicine views all approved or authorized COVID-19 vaccines as highly effective at preventing serious disease, hospitalization, and death from COVID-19. Learn more about coronavirus vaccine safety and what you need to know about the COVID vaccines.
  2. Get a flu shot. Even if you usually skip a flu shot, this is the year to make sure you get one. It is safe for you to go to the doctor for a flu shot. For the 2021–2022 flu season, the U.S. Centers for Disease Control and Prevention, or CDC, recommends that you get your flu shot in September or October. Ask your doctor if you should get a pneumonia shot, too.
  3. Don’t forget the kids. It’s important to ensure your children (over 6 months old) get flu shots — and any other vaccines they need. Kids age 12 and up are eligible to receive one of the current COVID-19 vaccines. Learn more about keeping up with routine vaccinations for babies and kids during the coronavirus pandemic.
  4. Care for yourself and your family with good nutrition, plenty of rest, proper hydration, regular exercise and stress management. And always stay home if you don’t feel well.
  5. Continue protecting yourself from the coronavirus. Even if you are tired of following coronavirus precautions such as washing your hands frequently, cleaning and sanitizing, wearing a face mask and physically distancing, it’s especially important now to keep up the good work — and encourage your family to do the same.

Coronavirus vs. Flu Deaths­

COVID-19: Current COVID-19 deaths*

Flu: The World Health Organization estimates that 290,000 to 650,000 people die of flu-related causes every year worldwide.

The COVID-19 situation continues to change, sometimes rapidly. Doctors and scientists are working to estimate the mortality rate of COVID-19. At present, it is thought to be substantially higher (possibly 10 times or more) than that of most strains of the flu.

*This information comes from the Coronavirus COVID-19 Global Cases map developed by the Johns Hopkins Center for Systems Science and Engineering.

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Updated: September 28, 2021