Questions and Answers on FluMist
(Influenza Virus Vaccine Live, Intranasal)
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)
Visit the CDC website at http://www.cdc.gov/ncidod/diseases/flu/
Updated:
May 19, 2008
