From the Guidelines
The main ingredients in flu vaccines typically include inactivated flu viruses or virus components, along with preservatives, stabilizers, and trace amounts of egg protein. Here's a more detailed breakdown:
- Flu virus strains: The vaccine contains either inactivated (killed) flu viruses or specific proteins from flu viruses, carefully selected each year based on predictions of which strains will be most prevalent 1.
- Preservatives: Thimerosal is sometimes used in multi-dose vials to prevent bacterial contamination, while single-dose vials and pre-filled syringes usually don't contain preservatives 1.
- Stabilizers: Ingredients like gelatin or sucrose are added to keep the vaccine stable during storage and transportation.
- Egg protein: Most flu vaccines are produced using chicken eggs, so they may contain small amounts of egg protein 1.
- Antibiotics: Trace amounts of antibiotics like neomycin may be present to prevent bacterial contamination during manufacturing.
- Buffer solutions: Ingredients like sodium phosphate help maintain the vaccine's pH balance. These components work together to stimulate your immune system to produce antibodies against the flu virus, providing protection without causing the actual illness, as the vaccine is made from highly purified, egg-grown viruses that have been made noninfectious (i.e., inactivated) 1. It's essential to note that the specific ingredients may vary slightly between different vaccine manufacturers and formulations.
From the FDA Drug Label
What are the ingredients in Fluzone vaccine? Fluzone vaccine contains 3 killed influenza virus strains. Other ingredients include formaldehyde and octylphenol ethoxylate. The preservative thimerosal is only in the multi-dose vial of Fluzone vaccine. The ingredients in the influenza (flu) vaccine are:
- 3 killed influenza virus strains
- Formaldehyde
- Octylphenol ethoxylate
- Thimerosal (only in the multi-dose vial) 2
From the Research
Ingredients in Influenza Vaccines
The ingredients in influenza vaccines can vary depending on the type of vaccine and the manufacturer. However, some common ingredients include:
- Inactivated or killed influenza virus, which can be grown in eggs or cells 3, 4, 5, 6
- Chemical inactivating agents such as β-propiolactone (BPL) or formaldehyde (FA) 3, 5
- Hemagglutinin (HA) and neuraminidase (NA) proteins, which are components of the influenza virus 3, 7
- Other ingredients such as preservatives, stabilizers, and adjuvants may also be present in some influenza vaccines
Vaccine Production Process
The production process for influenza vaccines typically involves:
- Growing the influenza virus in eggs or cells 3, 4, 5, 6
- Inactivating the virus using chemical or physical methods 3, 5
- Purifying and concentrating the inactivated virus 6
- Formulating the vaccine with other ingredients such as preservatives and adjuvants 6
Types of Influenza Vaccines
There are several types of influenza vaccines available, including:
- Inactivated influenza vaccines, which contain killed influenza virus 3, 4, 5, 6
- Live-attenuated influenza vaccines, which contain weakened influenza virus 6
- Recombinant influenza vaccines, which contain genetically engineered influenza virus proteins 6
- Virus-like particle (VLP) and nanoparticle vaccines, which are being developed as potential new vaccine platforms 6