FAQs About the Flu

Flu Vaccine Finder

Click on the Vaccine Finder to find flu shot resources near you. 

Influenza or “the flu” is a highly contagious respiratory illness that is caused by a virus. For people with cystic fibrosis, getting the flu may cause a worsening of symptoms and lead to a faster decline in lung function. 

To reduce the risk of getting and spreading the flu virus, there are steps you can take before and during the flu season (October through May).


How is the flu contagious?

Like many germs, the flu virus can spread by direct and indirect contact and through the air. To reduce the risk of getting and spreading the flu, it is important for you and everyone around you to follow infection prevention and control practices like hand washing and getting vaccinated.

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What are the symptoms of the flu?

In people with CF, the flu can lead to a severe lung infection, like pneumonia. If you have the flu, you may feel worse than you do with a typical lung infection or pulmonary exacerbation. Flu symptoms include:

  • Body aches and headache
  • Fatigue
  • Fever and chills
  • Increased cough
  • Sore throat

Contact your CF care center or doctor’s office as soon as you feel flu-like symptoms. Antiviral medications used to treat people for the flu are most effective if taken within 24 hours of the start of symptoms. These drugs may help lessen your symptoms or how long you are ill.

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How can I reduce my risk for getting the flu?

The following recommendations are intended to help people with CF reduce the risk of getting and spreading germs, like the flu.

  • Get vaccinated: The flu vaccine or “flu shot” can reduce the risk of getting the flu by helping the body fight off or increase its immunity to the flu virus.

    It is best to get the flu shot early since it can take around 2 weeks after vaccination for the body to build up its immunity to protect itself against the flu virus. The best time to get the flu shot is in September through October, but getting vaccinated in December or January is still helpful as flu season can last until spring.

    It is important to get the flu shot every year, since flu viruses are always changing. The flu vaccine cannot prevent all types of the flu virus, but it remains the best way to reduce the risk of getting the flu viruses that are most likely to make you sick in the current flu season.

    Since the flu is highly contagious, encourage everyone around you, especially family members or people who live with you, to also get vaccinated to reduce the risk of getting and spreading the flu virus.

  • Wash your hands: Use soap and water to wash your hands or clean them with an alcohol-based hand gel (especially after coughing or sneezing). This will help protect you and others around you.

  • Cover your cough: Use a tissue when you cough or sneeze. Throw the tissue away immediately, then wash your hands with soap and water or clean them with an alcohol-based hand gel. If you don’t have a tissue, cough or sneeze into your inner elbow. If you cough or sneeze into your hands, wash them immediately afterward.

  • Keep a safe distance: Try to stay at least 6 feet away from anyone who has a cold, the flu or an infection in all settings, both outdoors and especially indoors, such as in school or at work. If you do get sick, staying home will allow you to get rest and recover. It will also help prevent spreading flu to others.

  • Practice other good health habits: Get plenty of sleep, drink plenty of fluids, eat nutritious food, be physically active and manage your stress.

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Is the flu vaccine one shot or two?

Children ages 6 months through 8 years may need two shots of the flu vaccine annually to fully protect them against the flu. Experts generally recommend four weeks between the two shots. However, ask your doctor if your child needs one or two flu shots and how far apart they should be given.

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Where can I get the flu shot?

People with CF can usually get their flu shot at a CF Foundation-accredited care center and through primary care providers. Talk with your CF care center to find out whether it has the vaccine available. You can also find the closest place to get a seasonal flu vaccine from the Flu Vaccine Finder.

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Are there any side effects from the flu shot?

The flu shot does not give you the flu because the viruses in the flu shot are killed (inactivated). The risk of the flu shot causing serious harm is very small. However, like any vaccine, you could have mild side effects, which may include:

  • Soreness or mild aches
  • Redness or swelling where the shot was given
  • A low-grade fever

If these problems happen, they will begin shortly after the shot was given and usually last one to two days. However, if you are not feeling better or start to feel worse, call your doctor.

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What is the flu mist and is it safe for people with CF?

The flu vaccine spray (e.g., FluMist®) is sprayed into the nose and contains live but weakened flu viruses. The safety of the flu vaccine spray has not been established in people who have a lung disease like CF or asthma. The spray is only approved for people ages 2 to 49 years of age who do not have a history of severe allergic reaction to any component of the vaccine.

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When is it safe to return to school or work?

People with the flu should try and stay home for at least 24 hours after the fever is gone. (The fever should be gone without using a fever-reducing medicine, like acetaminophen or Tylenol®.) A fever is defined as 100.4 degrees Fahrenheit or 38 degrees Celsius or higher. Children should not take aspirin if they have the flu or any viral infection.

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Additional resources about germs and infection prevention and control

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Additional resources about the flu 

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Updated: 9/22/2014