Every Ingredient in a Vaccine Has a Purpose
Vaccines are made with specific ingredients that serve important roles in helping protect your health:
To Build Immunity
Vaccines help your body create antibodies that protect against disease. Some ingredients train your immune system to recognize and fight specific viruses or bacteria.
To Keep Vaccines Safe and Stable
Vaccines must remain safe and effective during storage and transport. Ingredients like stabilizers prevent contamination and help maintain potency over time.
To Boost Effectiveness
Certain ingredients called adjuvants, enhance your immune response so the vaccine works better.
Common Vaccine Ingredients & Their Roles
| Ingredient Type | Purpose | Examples / Where Found |
|---|---|---|
| Stabilizers | Keep vaccines effective after production | Sugars, gelatin (also found in Jell-O®, naturally in the body) |
| Adjuvants | Boost the immune response | Aluminum salts (found in water, infant formula, antacids, and antiperspirants) |
| Inactivating Agents | Kill viruses or inactivate toxins during manufacturing | Formaldehyde (found naturally in the body, fruits, and household items) |
| Cell Culture Materials | Help grow viruses or bacteria for the vaccine | Egg protein (found in eggs and egg-based foods) |
| Antibiotics (residual) | Prevent bacterial contamination during production | Neomycin, Kanamycin, Streptomycin (not penicillin, due to allergy risk) |
| Preservatives | Prevent contamination in multi-dose vials | Thimerosal (a safe form of mercury used only in some flu and Td vaccines) |
About Mercury in Vaccines
Most vaccines do not contain mercury. A few multi-dose flu and Td vaccines use thimerosal, which contains ethylmercury, a safe form that does not cause mercury poisoning. Thimerosal-free options are available.
Learn More About Vaccine Ingredients
The FDA oversees vaccine safety and effectiveness. You can find full ingredient lists and details for each approved vaccine on their website:
Visit FDA’s vaccine information page
Source: cdc.org