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Quadrivalent Influenza Vaccine

Questions & Answers

Note: On February 26, 2015, the Advisory Committee on Immunization Practices (ACIP) voted on its annual influenza vaccine recommendations. For 2015-2016, ACIP recommends annual influenza vaccination for everyone 6 months and older with either LAIV or IIV, with no preference expressed for either vaccine when either one is otherwise appropriate. More information on this vote is available at the CDC Newsroom. The LAIV content on this web page will be updated after the 2015-2016 recommendations are approved by the CDC Director and published in the MMWR.

What is quadrivalent flu vaccine?

The quadrivalent flu vaccine is designed to protect against four different flu viruses; two influenza A viruses and two influenza B viruses.

Why was the quadrivalent flu vaccine developed?

For years, flu vaccines were designed to protect against three different flu viruses (trivalent). This included an influenza A H1N1 virus, an influenza A H3N2 virus and one B virus. Experts had to choose one B virus, even though there are two very different lineages of B viruses that both circulate during most seasons. This meant the vaccine did not protect against the group of B viruses not included in the vaccine. Adding another B virus to the vaccine aims to give broader protection against circulating flu viruses.

Who can get the quadrivalent flu vaccine?

Different vaccines are approved for different age groups. There is a quadrivalent flu shot that can be given to children as young as 6 months of age. Other quadrivalent flu shots are approved for people 3 years and older. The quadrivalent nasal spray vaccine is approved for people 2 through 49 years of age who do not have contraindications to the nasal spray vaccine. Refer to the table of 2014-15 approved influenza vaccines in the U.S. for more information.

Who shouldn’t get the quadrivalent flu vaccine?

Different flu vaccines are approved for use in different groups of people. Factors that can determine a person's suitability for vaccination, or vaccination with a particular vaccine, include a person's age, health (current and past) and any relevant allergies, including an egg allergy.

Flu Shot:

Nasal Spray Vaccine:

Are any of the available flu vaccines recommended over the others?

CDC has not expressed a preference for which flu vaccine people should get this season except for one: Starting in 2014-2015, CDC recommends use of the nasal spray vaccine for healthy* children 2 years through 8 years of age when it is immediately available and if the child has no contraindications or precautions to that vaccine. If the nasal spray vaccine is not immediately available and the flu shot is, vaccination should not be delayed and a flu shot should be given. For more information about the new CDC recommendation, see Nasal Spray Flu Vaccine in Children 2 Years through 8 Years Old or the 2014-2015 MMWR Influenza Vaccine Recommendations.

While there will be more than one vaccine option for many people to choose from, including high-dose vaccine, intradermal vaccine and the regular flu shot, the only preferential recommendation is for the nasal spray vaccine in healthy* children 2 years through 8 years of age. The most important thing is for all people 6 months and older to get a flu vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.

(*“Healthy” in this instance refers to children 2 years through 8 years old who do not have an underlying medical condition that predisposes them to influenza complications.)

How much of the flu vaccines for the United States during 2014-2015 will be quadrivalent?

Of the 151 to 156 million doses of influenza vaccine projected to be available for the 2014-2015 season, manufacturers estimate that 76 million doses will be quadrivalent flu vaccine.

Is the quadrivalent flu vaccine safe?

Yes. Flu vaccines that protect against four flu viruses are made in the same way as the flu vaccines that have been around for years that protect against three flu viruses. The difference is the addition of another vaccine virus. Studies have shown that vaccines made to protect against four flu viruses have a safety profile similar to seasonal flu vaccines made to protect against three viruses, with similar—mostly mild—side effects. Hundreds of millions of people have safely gotten flu vaccines that protect against three flu viruses. Like all seasonal flu vaccines, vaccines that protect against four flu viruses will be monitored for their safety and effectiveness.

Quadrivalent vaccine cannot cause influenza illness, because the vaccine viruses used to make it are ‘inactivated’ (killed) or attenuated (weakened). See “Can the flu vaccine give me the flu?” for information about flu vaccine side effects.

What should people do if they can’t find available quadrivalent vaccine?

Don’t delay getting a flu vaccine if you cannot locate a quadrivalent vaccine. The important thing is to get vaccinated against influenza. Find flu vaccine near you using the vaccine finder at Call ahead to ask about availability if you are interested in a specific type of vaccine.

Will the quadrivalent flu vaccine be more expensive than the trivalent flu vaccine?

Quadrivalent flu vaccines may cost more than trivalent vaccines. Ask your insurance provider or doctor to find out how much you may need to pay and how much of the cost is covered by insurance.