FluMist is the trade name for a nasal spray influenza vaccine. The vaccine contains live but weakened virus particles that provoke antibody production against influenza but do not cause disease. FluMist is a live, attenuated influenza vaccine or LAIV. The U.S. Food and Drug Administration has approved LAIV for use in healthy people ages 2 to 49. The Centers for Disease Control and Prevention says LAIV is not to be used in pregnant women, children younger than 5 with a history of wheezing or asthma, and people with pre-existing medical problems. Talk with your doctor about whether a flu shot or the nasal spray is best for you.
Live, Attenuated Influenza Viruses
LAIV contains live but significantly weakened influenza virus particles. The seasonal flu vaccine typically contains three different strains of influenza viruses. In a 2007 article published in the New England Journal of Medicine, Dr. Robert Belshe and his colleagues reported LAIV was more effective in preventing influenza than a flu shot among children ages 6 months to 5 years. The superior immune protection induced by live attenuated viral vaccines compared to killed virus vaccines has also been reported with other diseases. Measles, mumps, rubella, polio, smallpox and varicella vaccines all use live, attenuated viruses to stimulate protective immunity against these diseases.
Buffers
The attenuated influenza virus particles are suspended in a buffer solution, which is the fluid matrix for delivering the virus into the nose. The FluMist buffer solution contains monosodium glutamate (MSG), gelatin, arginine, sucrose, potassium phosphate and ethylene diamine tetracetic acid (EDTA). FluMist does not contain thimerosal or other preservatives.
Gentamicin
FluMist contains a minute amount of the antibiotic gentamicin. The antibiotic is used to prevent bacterial contamination of the vaccine.
Trace Amounts of Eggs
Eggs are used to grow attenuated influenza viruses. After a period of incubation to allow the viruses to replicate (make more virus particles), they're harvested and separated from the eggs. However, trace amounts of egg may remain. People who have allergies to eggs or egg proteins should not take FluMist.
References
- Drugs.com: FluMist FDA Monograph
- Medimmune: FluMist Full Prescribing Information
- Centers for Disease Control and Prevention: The Nasal-Spray Flu Vaccine (Live Attenuated Influenza Vaccine [LAIV])
- Centers for Disease Control and Prevention: Key Facts about Seasonal Flu Vaccine
- Virology Online: Types of Vaccines
