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Flu Vaccine: What’s in it?

Should you get the flu (influenza) vaccine? Is it safe? To help you make an educated healthcare decision, Immunize Nevada has compiled a list of the ingredients used to make the annual flu vaccine. Each year, scientists create a flu vaccine based on the most prevalent flu strains that are expected during the upcoming flu season. The basic ingredients are the same year to year and we have listed them here.   

Ingredients you will find in flu vaccine

While different brands of flu vaccines have slightly different recipes, all ingredients are safe, well tested and serve to protect the recipient from getting flu and getting seriously ill from the disease. Flu vaccine ingredients fall into the following five basic categories.   

  1. Antigens
    These are the active ingredients that induce an immune response in our bodies. There are two types of antigens used in flu vaccines:
  • Dead, Inactivated Virus: This may be a dead, inactivated virus, like those used in the vaccine brands Afluria, Fluarix, FluLaval, Fluzone or FluceLvax. These dead viruses are not capable of replicating in your body. 
  • Live, Weakened Virus: The FluMist nasal spray flu vaccine contains a live but weakened virus.
  • Part of A Virus: Several flu vaccines contain only the proteins from the surface of the virus. Vaccine brand Fluad contains two proteins (hemagglutinin & neuraminidase). Brand Flublok contains one protein (hemagglutinin) which is made using recombinant DNA technology. 
  1. Adjuvants
    An adjuvant is an ingredient that helps create a stronger immune response in people receiving the vaccine. In other words, adjuvants help vaccines work better. Fluad is the only flu vaccine brand that contains an adjuvant (it’s called MF59). 
  1. Stabilizers
    Stabilizers help ensure vaccines remain stable and effective during shipping and storage. They are not associated with safety concerns with the exception of gelatin. Gelatin may pose a safety concern for those with gelatin-related allergies or be a concern for those who do not consume pork products. FluMist is the only vaccine that contains gelatin. 
  1. Preservatives
    Flu vaccines in multi-dose vials must contain a to safeguard against contamination of the vial. Thimerosal is the preservative used for multi-dose vials andahs been proven safe. However, most flu vaccines are now single dose. Most single-dose vials and pre-filled syringes of flu shot and the nasal spray flu vaccine do not contain a preservative because they are intended to be used once.

  2. Residual Byproducts
    Additional ingredients are needed to help combine vaccine ingredients together. These ingredients are removed once the vaccine is blended, but trace amounts may remain. Because residual amounts may remain in the vial, they are listed as ingredients, although the amounts are so small they have no impact on the vaccine recipient. 

Ingredients you will NOT find in flu vaccines

While there is a lot of misinformation about what is in flu vaccines, rest assured these ingredients are never found in flu vaccines distributed in the U.S.:

  • Fetal Cells
  • Gluten
  • Human DNA
  • Blood Products 
  • Soy
  • Microchips
  • COVID-19
  • Natural Rubber Latex

Your health is in your hands. Be an informed and educated health care consumer so you can best protect yourself and your family. For more information on vaccine safety, see the Immunize Nevada vaccine safety resource guide.