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Prepare Now for the Beginning of Flu Season

Denver, CO —


When is flu season?  

The start of influenza season varies with geographical location and from year to year.  We generally use October through March as the official “season” though cases occur both before and after this time period.  In Colorado, the peak season usually starts in December or January and starts to wane in February.

How bad is this flu season expected to be?  

It is impossible to predict the severity of the coming flu season.  It is better to expect influenza and prepare for it with vaccination and good hygiene practices, outlined below.  

I see some places already advertising flu shots. When is the right time to get a flu shot? 

It is fine to get the vaccine anytime starting in September. You should probably plan to receive it by the end of October at the latest.  It takes two weeks to build up immunity after vaccination, and you want to be protected in time for the holiday travel and shopping that starts around Thanksgiving, when influenza really begins spreading throughout the nation.

What are the different types of flu vaccines?  

The vaccine comes in two basic forms – an inactivated vaccine, which contains portions of dead virus, and a weakened vaccine with contains live, but weakened strains of the virus, which do not cause illness.

Inactivated virus:

  1. Standard inactivated trivalent- “the shot.”  This contains two “A-type” viruses and one “B-type” virus.
  2. Newer inactivated quadrivalent- also a shot, that contains two “A-type” viruses but adds a second “B-type” virus.
  3. A high-dose of the trivalent inactivated vaccine (the shot) is available to those > 65 years of age.
  4. A very limited supply of inactivated vaccine for people age 18 to 49 years of age with severe egg allergies that is made without the use of eggs at any step of the manufacturing process.

Weakened vir​us:

  1. The nasal vaccine that contains weakened viral strains of live virus- this is available in both trivalent and quadrivalent vaccines.

Information on the different types and supplies of vaccine in the United States is available at

Not all forms will be available at National Jewish Health.  

How do I know which flu shot(s) is right for me?   

Many factors are used to determine this.  It is best to discuss this with your health care provider.  

How long does a flu shot last? Is it possible I could get it too soon to protect me all season long? 

The shot and intranasal vaccines provide protection for about six months.  As a general rule of thumb, any time after the first part of September through the end of October should give you the most protection.

I have an egg allergy; can I still get a flu shot?  

The flu vaccine is grown on egg protein. In the past, the flu vaccine has been given following a protocol in smaller doses under observation. Research has shown this is not necessary in many cases. Based on research there are new recommendations for people who have a history of egg allergy. If a person has an egg allergy and is able to eat eggs, the person can receive the flu vaccine. If the person has an egg allergy and develops hives the person can receive the flu vaccine, but is observed closely for 30 minutes. If the person has an egg allergy and develops other symptoms referral to an allergist may be recommended. The person can still receive the flu vaccine, but is observed closely for 30 minutes.

Last year a limited supply of vaccine became available for people 18 to 49 yea of age. It is available in the United States this year from only one source and is called FluBlock®.  If you have an egg allergy please discuss this with your doctor.  Mild egg allergies may not prevent you from getting the vaccine made with eggs but this is a decision best made by you and your physician.    

If I get a flu shot does that guarantee I won’t get the flu this year? 

No.  People build up differing levels of immunity after vaccination, and, while most are protected, some people can still get the flu even after vaccination. Also, there are many strains of influenza that circulate each year some of which are not included in the vaccine. The vaccines are manufactured months in advance based on what are the most likely strains to be seen during that season.  So, even those who are healthy and build up good immunity following vaccination can get influenza due to contact with a different strain that was not in the vaccine.   Research is being done to try and find a “universal” vaccine that will one day protect us from all strains of influenza.  

Other than a flu shot, what are some of the things I can do to prevent getting the flu? 

  • This starts with the basics of keeping ourselves as healthy as we can through diet, exercise, adequate sleep. Specifics that help prevent the spread of flu and other respiratory virus include:
  • Covering your cough and asking others to cover their coughs.
  • Frequent hand washing or using waterless hand sanitizers.  Hand sanitizers are great since small ones are inexpensive and can be easily carried in a pocket or purse when out and about.  Many retail locations place disinfectant wipes near where you pick up shopping carts and baskets or hand sanitizers where you order food in cafes.  If your store does not provide this service, ask the manager to do this.  
  • Refrain from rubbing your mouth, eyes and nose. Even with frequent hand washing your hands can get virus on them, and the mouth, eyes and nose are prime entry points for the virus into the body. 
National Jewish Health is the leading respiratory hospital in the nation. Founded 125 years ago as a nonprofit hospital, National Jewish Health today is the only facility in the world dedicated exclusively to groundbreaking medical research and treatment of children and adults with respiratory, cardiac, immune and related disorders. Patients and families come to National Jewish Health from around the world to receive cutting-edge, comprehensive, coordinated care. To learn more, visit the media resources page.

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