FLU VACCINE
Vaccine Ingredient Safety
Vaccine ingredients are tested for safety before they are manufactured. Learn more about each ingredient:
SALTS
- Sodium & aluminum salts are used to normalize the salt balance in the human body
- Some salts split the virus into smaller pieces to activate the immune system for adjuvanted vaccines
SUGARS
- Adding sugar stabilizes the vaccine ingredients so that they are less sensitive to heat/cold
- The sugars used in vaccines are the same ones used to stabilize food products
EMULSIFIERS
- Help mix ingredients that would normally not mix together (think oil + vinegar!)
- The amounts used in vaccines are much smaller than what is used in other things you put into your body - like food and cosmetics
MF59 Adjuvant
- Only used in adjuvanted vaccines for people 65+ to create a stronger immune response
- The main ingredient, squalene oil, occurs naturally in humans, animals, and plants
THIMEROSAL
- Preservative used to prevent contamination in multi-dose vials
- Most flu vaccines are single-vial and thus do not contain thimerosal
- Thimerosal is metabolized by the body as ethylmercury, which is not the same as methylmercury, and does not cause poisoning
FORMALDEHYDE
- Formaldehyde is naturally occurring in apples, bananas, pears, and more
- Used to kill the flu viruses so that the viruses in the vaccine teach your body to fight off and don't make you sick
- The amount used in vaccines is much smaller than the amount that naturally occurs in the body
ANTIBIOTICS
- Can be leftover from the manufacturing process to prevent contamination of bacteria into the vaccines
- Most are removed during the purification process
- The amount leftover is microscopic
EGG PROTEIN
- Only present in vaccines grown in eggs
- Most is filtered out when the viruses are extracted from the eggs they were grown in
Learn more about flu and flu vaccines:
Page last reviewed: November 2021.