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COVID-19 vs. the Flu

Unwell woman laying on couch

September 20, 2021

COVID-19 may be the contagious illness that is top of mind as we head into fall, but health experts say you still must get your flu shot.

Flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat and sometimes the lungs. Symptoms range from mild to severe and can lead to death. The best way to prevent flu is by getting a flu vaccine annually.

Flu activity typically begins in late October to early November and lasts until the end of spring or late May. The height of flu season is usually between December and February.

Dana Hawkinson, MD, medical director of infection prevention and control at The University of Kansas Health System, says it’s critical that everyone 6 months of age and older get an annual flu vaccine.

"Talk with your healthcare provider, but do not miss an opportunity to receive a flu vaccination when it becomes available," says Dr. Hawkinson.

Dr. Hawkinson says many of the steps we take to protect ourselves from contracting the deadly coronavirus will also help during flu season. COVID-19 has caused more than 670,000 deaths in the United States since March 2020.

"Wearing a mask, washing your hands frequently and keeping your distance from others – those measures will help protect us from influenza as well," he says.

Both COVID-19 and flu can have varying signs and symptoms, ranging from no symptoms to severe symptoms. Common symptoms that COVID-19 and flu share include:

  • Fever or feeling feverish/chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Vomiting or diarrhea (most often in children)

Both COVID-19 and flu can spread among people who are in close contact with one another and both are spread primarily by droplets made when people with the illness cough, sneeze or talk. The droplets can land in the mouths, noses or eyes of people nearby or be inhaled into the lungs.

Talk with your healthcare provider, but do not miss an opportunity to receive flu vaccination when it becomes available. ‒ Dana Hawkinson, MD

Medical director, infection prevention and control

Differences between the flu and COVID-19

Flu usually comes on suddenly, anywhere from 1 to 4 days after infection, while COVID-19 symptoms may appear 2-14 days after exposure to the virus. According to the Centers for Disease Control and Prevention (CDC), someone exposed to COVID-19 typically develops symptoms 5-6 days after being infected, but that time span can vary.

Another symptom of COVID-19 that distinguishes it from the flu is a change in or loss of taste or smell that often occurs. Temporary loss of smell and taste has been tied to COVID-19 infection.

The CDC wants to ensure you take steps to care for yourself by getting a flu shot and understanding the difference between COVID-19 and the flu.

  • Influenza (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 called SARS-CoV-2, and flu is caused by infection with influenza viruses. Because COVID-19 is a new virus, it seems to be spreading through the human population much faster than flu, and there is still a significant chunk of the U.S. population that has not yet received a vaccine. With the flu, most of us are carrying some level of antibody protection from a previous year's exposure or from a vaccine. Additionally, the case fatality rate is much higher for COVID-19 than the flu.

  • The CDC believes it's likely that flu viruses and the virus that causes COVID-19 will both be spreading this fall and winter. In this context, getting a flu vaccine will be more important than ever. CDC recommends that all people 6 months and older get a yearly flu vaccine.

  • For both COVID-19 and flu, it’s possible to spread the virus for at least 1 day before experiencing any symptoms. But, if a person has COVID-19, they may be contagious for a longer time period than if they had flu. In addition, many people with COVID-19 do not have symptoms or have mild symptoms they don’t recognize. Because they do not realize they are ill, they are more likely to spread the virus to others.

  • Flu and COVID-19 can both result in serious illness, including illness resulting in hospitalization or death. While there is still much to learn about COVID-19, it is more deadly than seasonal influenza. COVID-19 has claimed the lives of more than 670,000 Americans since March 2020, shut down most major sports, closed schools, affected travel and had a devastating impact on the U.S. economy. The same cannot be said about the flu.

  • September and October are good times to get vaccinated. However, as long as flu viruses are circulating, vaccination should continue, even in January or later.

  • Yes. It is possible to have flu, as well as other respiratory illnesses, and COVID-19 at the same time. Health experts are still studying how common this can be. Some of the symptoms of flu and COVID-19 are similar, making it hard to tell the difference between them based on symptoms alone. Diagnostic testing can help determine if you are sick with flu or COVID-19.

  • Yes. The CDC recently announced that it is safe to receive flu vaccines and COVID-19 vaccines simultaneously. All people at least 6 months of age without certain underlying conditions can receive a flu vaccine, while those 12 years and older can receive a COVID-19 vaccine.

  • Yes. CDC has developed a test that will check for A and B type seasonal flu viruses and SARS CoV-2, the virus that causes COVID-19. The test is used by U.S. public health laboratories. Testing for these viruses at the same time gives public health officials important information about how flu and COVID-19 are spreading and what prevention steps should be taken. The test also helps public health laboratories save time and testing materials, and to possibly return test results faster.

  • No. The new test is designed for use at CDC-supported public health laboratories at state and local levels, where it will supplement and streamline surveillance for flu and COVID-19. The use of this specialized test will be focused on public health surveillance efforts and will not replace any COVID-19 tests currently used in commercial laboratories, hospitals, clinics and other healthcare settings. If you want to receive a test, speak to your healthcare provider.

  • Getting a flu vaccine will not protect against COVID-19; however, flu vaccination has many other important benefits. Flu vaccines help reduce the risk of flu illness, hospitalization and death. Getting a flu vaccine this fall will be more important than ever, not only to reduce your risk from flu but also to help conserve potentially scarce healthcare resources.

  • If COVID-19 symptoms persist beyond 48 hours after getting the flu vaccine, you may need a COVID-19 test. Call your healthcare provider for direction. They may also tell you to quarantine until your COVID-19 test result becomes available.

Call your provider’s office or 913-588-1227 to schedule a flu shot. Flu shots will be administered 8 a.m.-4 p.m. Mondays-Fridays on a walk-in basis at The University of Kansas Health System Medical Pavilion, Level 4, on the main campus.

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