Flu season is coming up soon, but have you ever thought about how the vaccines are made? Currently there are three influenza vaccine production technologies that are utilized in the United States.  All meet U.S. Food and Drug Administration (FDA) approval. They are:

  • Egg-based flu vaccine
  • Cell-based flu vaccine
  • Recombinant flu vaccine

Egg-based flu vaccine

The egg- based process has been used for some 70 years. When the current year’s flu virus strains have been identified by the World Health Organization (WHO) Influenza Surveillance System and approved for use in the United States by the FDA, these candidate vaccine viruses (CVVs) are injected into fertilized hen eggs and incubated for several days to allow the viruses to replicate. For flu shots, the influenza viruses are then inactivated (killed), and the virus antigen is purified. This method requires large numbers of chicken eggs and usually takes longer than other methods to produce a vaccine.

Cell-based flu vaccine

The cell-based production process for flu vaccines was approved by the FDA in 2012. However, until recently, this production process also began with egg-grown candidate vaccine viruses (CVVs). In August of 2016, the FDA issued an approval for Seqirus, the sole FDA approved cell-based flu vaccine manufacturer in the U.S. to use cell grown CVVs. Cell-based flu vaccine production does not require chicken eggs because the vaccine viruses used to make the vaccine are grown in animal cells. Cell culture technology has the potential for a faster start-up of the vaccine manufacturing process.

Recombinant flu vaccine

The recombinant method of producing flu vaccine was approved by the FDA for use in the U.S. market in 2013. This production method does not require an egg grown vaccine virus and does not use chicken eggs at all in the manufacturing process. It uses an influenza virus protein that is made by genetically modifying a virus that infects insect cells to produce the flu vaccine protein. The protein, as in other flu vaccines, then triggers the immune system of the person receiving the vaccine to make protective antibodies. Currently, recombinant flu vaccine is the only 100% egg free vaccine on the U.S. market.

As with all health related issues, it is best to have a discussion with your physician in making the determination as to which flu vaccine formulation is best for you.

For further information: www.cdc.gov/flu/protect/vaccine/how-fluvaccine-made.htm