Influenza (Flu) FAQ : The Nasal-Spray Flu Vaccine

by CDC

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Live Attenuated Influenza Vaccine (LAIV)

What is the nasal-spray flu vaccine (or LAIV)?

The nasal-spray flu vaccine (sometimes called LAIV for Live Attenuated Influenza Vaccine) is a new flu vaccine that was licensed in 2003. It is different from the other licensed influenza vaccine (also called the "flu shot") because it contains weakened live influenza viruses instead of killed viruses and is administered by nasal spray instead of injection.

How does the nasal-spray flu vaccine (LAIV) work?

The nasal-spray flu vaccine contains three different live (but weakened) influenza viruses. When the viruses are sprayed into the nose, they stimulate the body's immune system to develop protective antibodies that will prevent infection by naturally occurring influenza viruses.

The live viruses in the nasal-spray flu vaccine (LAIV) are attenuated, cold-adapted, and temperature sensitive. What does this mean?

Attenuated means the viruses are weakened and will not cause severe symptoms often associated with influenza illness. Cold-adapted and temperature sensitive mean the viruses can grow in the nose and throat, but not in the lower respiratory tract where the temperature is higher.

How effective is the nasal-spray flu vaccine (LAIV)?

In one large study among children aged 15-85 months, the nasal-spray flu vaccine (LAIV) reduced the chance of influenza illness by 92% compared with placebo. In a study among adults, the participants were not specifically tested for influenza. However, the study found 19% fewer severe febrile respiratory tract illnesses, 24% fewer respiratory tract illnesses with fever, 23-27% fewer days of illness, 13-28% fewer lost work days, 15-41% fewer health care provider visits, and 43-47% less use of antibiotics compared with placebo.

Who can be vaccinated with the nasal-spray flu vaccine (LAIV)?

LAIV is approved for use in healthy people between the ages of 5 and 49 years.

Who should not be vaccinated with the nasal-spray flu vaccine (LAIV)?

• People less than 5 years of age
• People 50 years of age and over
• People with a medical condition that places them at high risk for complications from influenza, including those with chronic heart or lung disease, such as asthma or reactive airways disease; people with medical conditions such as diabetes or kidney failure; or people with illnesses that weaken the immune system, or who take medications that can weaken the immune system.
• Children or adolescents receiving aspirin
• People with a history of Guillain-Barré syndrome, a rare disorder of the nervous system
• Pregnant women
• People with a history of allergy to any of the components of LAIV or to eggs

Should the nasal-spray flu vaccine (LAIV) be given to patients with chronic diseases other than those specifically listed above?

No. The nasal-spray flu vaccine is approved for use only in healthy people between the ages of 5 and 49 years.

Are there any contraindications to giving breastfeeding mothers LAIV (sold commercially as FluMist)?

Breastfeeding is not a contraindication for FluMist.

Can the nasal-spray flu vaccine (LAIV) be given to patients when they are ill?

The nasal-spray flu vaccine (LAIV) can be given to people with minor illnesses (e.g., diarrhea or mild upper respiratory tract infection with or without fever). However, if nasal congestion is present that might limit delivery of the vaccine to the nasal lining, then delaying of vaccination until the nasal congestion is reduced should be considered.

Can people receiving the nasal-spray flu vaccine (LAIV) pass the vaccine viruses to others?

In clinical studies, transmission of vaccine viruses to close contacts has occurred only rarely. The current estimated risk of getting infected with vaccine virus after close contact with a person vaccinated with the nasal-spray flu vaccine is low (0.6%-2.4%). Because the viruses are attenuated and cold-adapted, infection is unlikely to result in influenza illness symptoms since the vaccine viruses have not been shown to mutate into typical or naturally occurring influenza viruses.

Can contacts of people with weakened immune systems get the nasal-spray flu vaccine (LAIV)?

People who are in contact with others with severely weakened immune systems when they are being cared for in a protective environment (for example, people with hematopoietic stem cell transplants), should not get LAIV. People who have contact with others with lesser degrees of immunosuppression (for example, people with diabetes, people with asthma taking corticosteroids, or people infected with HIV) can get LAIV.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.