U.S. flag An official website of the United States government
  1. Home
  2. Vaccines, Blood & Biologics
  3. Vaccines
  4. Questions and Answers - FluMist Quadrivalent (Influenza Virus Vaccine Live, Intranasal)
  1. Vaccines

Questions and Answers - FluMist Quadrivalent (Influenza Virus Vaccine Live, Intranasal)

  1. What is FDA announcing?
    FDA is announcing that it has approved the first quadrivalent vaccine, FluMist Quadrivalent, to prevent seasonal influenza disease. The vaccine will contain the two influenza A and two influenza B virus strains most likely to spread and cause illness during the influenza season.
  2. What is the difference between a quadrivalent influenza vaccine and a trivalent influenza vaccine?
    Traditionally, the influenza vaccines licensed by FDA for use in the United States contain three different influenza virus strains (trivalent formulation). These strains represent the viruses predicted to be in circulation in the United States during the influenza season.

    There are two types of influenza viruses included in each year’s influenza vaccine, human influenza A and influenza B. The trivalent seasonal influenza vaccine contains two A (H1N1 and H3N2) virus strains and one B (Victoria or Yamagata) virus strain.  

    During the influenza season there may be two different B strains circulating at the same time that are different enough that vaccination against one will not provide protection against the other, or the B strain selected for inclusion in the trivalent influenza vaccine may not be the influenza B strain that eventually circulates causing illness.  

    The quadrivalent vaccine contains four (two A and two B) influenza virus strains. Inclusion of a second B strain increases the likelihood for adequate protection against circulating strains. FDA approved the quadrivalent influenza vaccine after determining that it was safe and effective.
  3. What is FluMist Quadrivalent vaccine and who can use it?
    FluMist Quadrivalent is manufactured in the same way as FluMist (trivalent) vaccine. Both vaccines are manufactured by MedImmune LLC, but FluMist Quadrivalent contains four strains of influenza virus, whereas FluMist contains three strains. The quadrivalent vaccine includes a second B influenza virus strain. Like FluMist (trivalent), the quadrivalent vaccine contains weakened forms of the virus strains and is administered as a spray into the nose. FDA has approved it for use in individuals 2 through 49 years of age.
  4. How was the safety and effectiveness of FluMist Quadrivalent evaluated?
    The safety and effectiveness of FluMist Quadrivalent is supported by studies conducted previously with FluMist and three new clinical studies with FluMist Quadrivalent conducted in the United States in approximately 4,000 children and adults. Studies compared FluMist Quadrivalent to two FluMist vaccines, each formulated to contain one of the two B strains included in FluMist Quadrivalent. The studies demonstrated that the immune responses and reactions were similar in study participants who received FluMist Quadrivalent and those who received FluMist.
  5. What are the most common reactions associated with FluMist Quadrivalent?
    The reactions reported by study participants were similar between those receiving FluMist Quadrivalent and FluMist. The most commonly reported reactions were runny or stuffy nose in both children and adults, and headache and sore throat in adults.
  6. How is the vaccine administered?
    FluMist Quadrivalent is administered as a single-dose spray (0.2 mL) into the nose. Approximately one-half of the contents should be administered into each nostril. 

    Children 2 years through 8 years of age not previously vaccinated with any influenza vaccine need two doses at least one month apart.

    Children 2 years through 8 years of age of who have been previously vaccinated with influenza vaccine need one dose.

    Individuals 9 through 49 years of age need one dose.
  7. Are there any individuals who should not receive FluMist Quadrivalent?
    Yes, although each individual should check with their health care provider before receiving any influenza vaccine, FluMist Quadrivalent should not be given to the following people: 
  • Individuals who have had a severe allergic reaction to any component of FluMist Quadrivalent, including egg protein, gentamicin, gelatin, and arginine, after a previous dose of any influenza vaccine.
  • Children and adolescents ages 2 through 17 years who are receiving aspirin or aspirin containing therapy, because of the association of Reye’s syndrome with aspirin and influenza infection. Avoid giving aspirin or medicines containing aspirin to this age group during the first 4 weeks after vaccination, unless clearly needed.

    It is important to note that FluMist Quadrivalent is not approved for use in children less than two years of age because of an increased risk of hospitalization and wheezing.  
  1. What is the difference between FluMist Quadrivalent, which is a live attenuated influenza virus (LAIV) vaccine and the influenza vaccine (a “shot”) that is made from inactivated viruses?
    FluMist Quadrivalent contains attenuated (weakened) influenza viruses. The weakened viruses are designed so that they cannot cause infection in the lungs or other areas of the body where warmer temperatures exist.  

    FluMist Quadrivalent is administered by spraying into the nose. Inactivated influenza vaccines contain killed viruses and are administered into a muscle using a needle.

    FluMist Quadrivalent is approved for individuals 2 through 49 years of age. Inactivated influenza vaccines, depending on the vaccine manufacturer, are approved for different age groups, including children as young as 6 months of age and adults over the age of 50 years.  
  2. Is it possible to get influenza from FluMist Quadrivalent vaccine?
    The viruses in the vaccine do not cause influenza illness because they have lost disease-causing properties. The vaccine can cause reactions, most of which are mild and do not require any treatment. 
  3. What is the best time of year to receive the seasonal influenza vaccine?
    All vaccines to prevent influenza, including FluMist Quadrivalent, should be administered prior to exposure to influenza. You can get the vaccine as soon as it is available – typically in the fall, but getting it anytime throughout the winter months when influenza season often peaks is also appropriate. Influenza disease generally occurs in the U.S. between November and May.
  4. Do I need to be vaccinated annually to prevent influenza?
    Yes, annual vaccination is important because influenza viruses can change, and the vaccine may also change from year-to-year. Therefore, it is important to get the vaccine every year for the new influenza season.
Back to Top