Nasal Spray Flu Vaccine
getting flu mist

Nasal Spray Flu Vaccine

The nasal-spray flu vaccine (sometimes called LAIV for Live Attenuated Influenza Vaccine) is made using eggs and contains the same viruses that the flu shot contains. It is different, however, because it contains weakened live viruses instead of killed viruses that are contained in the flu shot, and it is administered by nasal spray rather than injection. It does not contain Thimerosal.

The weakened, temperature-sensitive viruses in the nasal spray vaccine can grow in the nose and throat, but not in the lower respiratory tract where the temperature is higher. The weakened viruses stimulate the body to produce antibodies against flu disease, but they are not strong enough to cause illness. Studies have shown the nasal spray vaccine to be very effective in preventing people from becoming ill with the flu.

Healthy people between 2 and 49 years of age can get the nasal spray vaccine.

Ineligible for Intranasal Flu Vaccine

The following people should not get the intranasal flu vaccine:

  • Adults 50 years of age or older
  • Children younger than 2
  • People who have long-term health problems, such as:
    • Heart, lung, or kidney disease
    • Metabolic disease, such as diabetes
    • Asthma, including children with a history of recurrent wheezing
    • Anemia and other blood disorders
  • People with a weakened immune system due to:
    • HIV/AIDS or another disease that affects the immune system
    • Long-term treatment with drugs that weaken the immune system, such as steroids
    • Cancer treatment with x-rays or drugs
    • Children or adolescents on long-term aspirin treatment (these people could develop Reye syndrome if they get the flu)
  • Pregnant women
  • Anyone with a history of Guillain-Barré Syndrome (GBS)

The flu shot (inactivated vaccine) is preferred over live, intranasal influenza vaccine for physicians, nurses, family members, or anyone else coming in close contact with anyone with a severely weakened immune system (that is, requiring care in a protected environment).

Risks of Intranasal Influenza Vaccine

A vaccine, like any medicine, could possibly cause serious problems, such as severe allergic reactions; however, the risk of a vaccine causing serious harm, or death, is extremely small.

Chances of live influenza vaccine viruses spreading from person to person are very small. Even if such spread should occur, it is unlikely to cause illness. Live, intranasal influenza vaccine can cause mild symptoms in the recipient (see below).

Mild Reactions to the Nasal Spray Vaccine

Some children and adolescents have reported mild reactions, including:

  • Runny nose, nasal congestion, or cough
  • Fever
  • Headache and muscle aches
  • Abdominal pain or occasional vomiting or diarrhea

Some adults have reported:

  • Runny nose or nasal congestion
  • Sore throat
  • Cough, chills, tiredness/weakness
  • Headache

These symptoms do not last long and will go away on their own. Even when they occur after vaccination, they may not be caused by the vaccine.

Severe Reactions to the Nasal Spray Vaccine

Life-threatening allergic reactions from vaccines are very rare. If such a reaction were to occur, it would happen within a few minutes to a few hours after the vaccination.

These reactions probably result from hypersensitivity to egg protein used in manufacturing the vaccine. Persons who have had hives or swelling of the lips or tongue, or who have experienced acute respiratory distress or collapse after eating eggs, should consult a physician to determine if the vaccine should be administered.

Symptoms of life-threatening allergic reactions include:

  • Hives
  • Swelling of the lips or tongue
  • Swelling around the heart
  • Allergic asthma
  • Difficultly breathing

If these signs occur, call a doctor or get the person to a doctor as soon as possible. Tell the doctor what happened, the date and time it happened, and when the vaccination was given.

If rare reactions occur with any new product, they may not be identified until many thousands, or millions, of people have used the product. Like all vaccines, live, intranasal influenza vaccine is being monitored for unusual or severe problems.

For More information

  • Ask your doctor or nurse. They can give you the vaccine package insert or suggest other sources of information.
  • Contact Boulder County Public Health at 303-413-7500.
  • Contact the Centers for Disease Control and Prevention (CDC) at 1-800-232-2522 (English) or 1-800-232-0233 (Español) or online at

Please Note: All information is general in nature and should not substitute seeking proper medical attention.

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