What Is a Live Attenuated Influenza Vaccine?

Nasal Spray Flu Vaccine. Dave Bradley Photography/The Image Bank/Getty Images

The Live Attenuated Influenza Vaccine (LAIV), commonly known as FluMist, is not recommended for use during the 2017-2018 flu season. The CDC's Advisory Committee on Immunization Practices voted to recommend against its use due to evidence that it was not effective at preventing the flu during the previous two flu seasons. Although it may be available in some places, both the CDC and the American Academy of Pediatrics have recommended against its use at this time. 


Most influenza vaccines - or flu shots - are made from killed viruses. This means that although a very tiny amount of the influenza virus is injected into your body, it is dead and cannot replicate to make you sick. 

However, the nasal flu vaccine (FluMist) is different. It is a live attenuated influenza vaccine (LAIV), meaning it is made from a weakened live flu virus. The process it goes through when it is manufactured makes it unable to survive in the warm parts of your body such as the lungs, but it is able to produce an immune response while it is in your nose, creating antibodies against the flu which will protect you if you are exposed to the flu during the rest of flu season. 

Who Is It For?

FluMist is approved for use in people age 2 to 49. 

Who Should Avoid It?

LAIV nasal spray flu vaccines should not be given to people:

  • Under the age of 2
  • Age 50 or older
  • Pregnant women
  • Who care for people with severely compromised immune systems (such as those who have just received a bone marrow transplant)
  • Ages 2 to 4 who have a history of wheezing in the past 12 months

How Is It Different?

Aside from the explanation above, the live attenuated influenza vaccine has some other distinct differences when compared to a traditional flu shot. 

It is a nasal spray vaccine, which means no needles are involved. A small syringe applicator is used to spray half of the vaccine into each nostril. If you are sick with an upper respiratory infection or have a lot of congestion, the vaccine may not be as effective. Talk to your health care provider about how you are feeling to determine if you need to delay the vaccine until your congestion has improved. 

FluMist is now a quadrivalent flu vaccine, meaning it includes four strains of influenza as opposed to the three included in the traditional flu vaccine. It includes the three strains of influenza (one strain of H1N1, one strain of H3N2 and one strain of influenza B) that are included in all flu vaccines and also contains an additional strain of influenza B. All strains of influenza included in the vaccine each year are chosen by researchers who work together to determine which types of flu are most likely to cause illness the following flu season.


The live attenuated influenza vaccine is a great option for many people. If want protection from the flu without the pain of a shot, talk to your health care provider about FluMist. 


"Live Attenuated Influenza Vaccine [LAIV] (The Nasal Spray Flu Vaccine)". Types of Flu 9 Sep 14. Questions & Answers. Seasonal Influenza (Flu). Centers for Disease Control and Prevention. US Department of Health and Human Services. 23 May 15. 

"Advisory Committee on Immunization Practices (ACIP) Reaffirms Recommendation for Annual Influenza Vaccination". CDC Newsroom Releases 26 Feb 15. Centers for Disease Control and Prevention. US Department of Health and Human Services. 22 May 15. 

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