Vaccines, Blood & Biologics
FluMist (Intranasal Influenza Virus Vaccine) Questions and Answers
What is FluMist approved for?
FluMist is a live attenuated influenza virus vaccine (LAIV) approved to prevent illness caused by influenza A and B viruses in individuals 2-49 years of age.
What is the difference between FluMist, a live attenuated influenza virus (LAIV) and the flu shot that is made from inactivated viruses?
Both LAIV and inactivated influenza vaccine contain strains of influenza viruses that are matched to protect against influenza strains that are likely to circulate each year. Viruses for both vaccines are grown in eggs. Because circulating strains of influenza virus change from year to year, each year’s vaccine may be different from the preceding year. Therefore, both vaccines are administered annually to provide optimal protection against influenza infection.
Inactivated vaccines are produced by killing the flu viruses; the killed viruses cannot cause influenza.
FluMist contains attenuated (or weakened) viruses. These weakened strains usually do not cause illness because they have lost virulence (disease-causing properties). However, there is a possibility that they can still reproduce and cause disease.
FluMist is sprayed in the nose, whereas inactivated influenza vaccine is given with a needle in the arm. FluMist is approved for use in individuals 2-49 years. Inactivated influenza vaccine is approved for use among persons aged ≥6 months, including those who are healthy and those with medical conditions.
Since vaccination against influenza is recommended for many people over the age of 49, why isn't FluMist recommended for individuals 50 years of age and older?
Studies with FluMist in individuals 50-64 years of age did not demonstrate effectiveness.
How many doses are recommended per season?
Children 2-8 years old need 1 or 2 doses, depending on whether they have been previously vaccinated with influenza vaccine.
Individuals 9-49 years old need only one dose per year.
How well does FluMist work?
In clinical trials, FluMist was evaluated in 20,228 individuals, including over 10,000 children 5-17 years old. FluMist was effective in preventing influenza in approximately 87 percent of children in the trial.
In children under age five, two studies compared FluMist to placebo (no vaccine). Both studies demonstrated the vaccine’s effectiveness in preventing influenza illness. A third study compared FluMist to an inactivated or "killed" seasonal influenza vaccine shot. The results showed that there were 53 cases of influenza disease among 3,900 children who received FluMist compared to 93 cases among the same number of children who received an inactivated or "killed" seasonal influenza vaccine shot.
In adults (ages 18-49 years), there were fewer upper respiratory illnesses with fever and fewer severe illnesses with fever in those who received FluMist versus those who received placebo.
As with any vaccine, FluMist may not protect 100% of individuals receiving the vaccine.
What are the most common side effects of FluMist?
In children, side effects can include nasal congestion, runny nose, headache, muscle aches, and slight fever. In adults, side effects can include runny nose, headache, sore throat, tiredness/weakness, muscle aches and cough. Fever is not a common side effect in adults.
However, as with medicines, problems may occur after administration of vaccines, such as allergic reactions, some of which may be severe. The risk of a vaccine causing serious harm or death is extremely small, and serious problems from flu vaccine are rare.
Are there certain people who may not be candidates for immunization with FluMist?
- Individuals with a history of hypersensitivity, especially anaphylactic reactions to eggs, egg proteins, gentamicin, gelatin, or arginine, or with life-threatening reactions to previous influenza vaccinations.
- Because Reye syndrome in children has been associated with administration of aspirin during influenza virus infections, children and adolescents 2-17 years of age should not receive FluMist if they are receiving aspirin or aspirin-containing therapy.
- Adults 50 years of age or older.
- Children under the age of 2 should not receive FluMist because there was an increased risk of hospitalization and wheezing for this age group during the clinical trials.
- Administration of FluMist to persons with a compromised immune system should be based on careful consideration of potential benefits and risks. Data supporting the safety and effectiveness of FluMist in this population are limited. In addition, FluMist is a live virus vaccine, and has the potential for transmission to household contacts that have a weakened immune system. FluMist recipients should avoid close contact after receiving the vaccine.
- Unless the potential benefit outweighs the potential risk, FluMist should not be administered to any individuals with asthma and children less than 5 years of age with recurrent wheezing because of the potential for increased risk of wheezing after vaccination.
- FluMist should not be administered to individuals with severe asthma or active wheezing because these individuals have not been studied in clinical trials.
- The safety of FluMist has not been established in people with underlying medical conditions that may predispose them to complications following influenza infection, such as heart disease, diabetes, kidney failure, etc.,.
- Animal reproduction studies have not been conducted with FluMist. It is not known whether FluMist can cause fetal harm when administered to pregnant women or can affect reproduction capacity. FluMist should be given to a pregnant woman only if clearly needed.
- If Guillain-Barré Syndrome (GBS) has occurred within 6 weeks of any prior influenza vaccination, the decision to give FluMist should be based on careful consideration of the potential benefits and potential risks.
- Before receiving any medication or vaccine, individuals should discuss with their health care provider.
Does FluMist contain thimerosal?
No, FluMist does not contain thimerosal or any other preservatives.
What is the best time of year to receive the flu vaccine?
Flu season in the United States can begin as early as October and can last as late as May. Flu vaccines should be administered prior to exposure to influenza. The peak of influenza activity varies from year to year, but generally occurs in the U.S. between late December and early March. Every year in the United States, more than 200,000 people are hospitalized with influenza and about 36,000 people die from its complications. While it is best to be immunized as soon as the vaccine is available, usually in September, getting the vaccine any time during influenza season is also appropriate because the influenza season often peaks late.
Will I need to receive an influenza vaccine every year?
Yes. Because yearly variation in the influenza strains is possible, annual immunization with an influenza vaccine is recommended.
Where can I obtain additional information?
We recommend that that you talk to your health care provider when you have any questions related to the medication(s) you receive. He or she can also suggest other sources of information.
Call your local or state health department.
Contact the Centers for Disease Control and Prevention (CDC):
Call 1-800-232-2522 (English)
Call 1-800-232-0233 (Español)
Product approval information