Understanding what goes into vaccines—active components, adjuvants, excipients, and preservatives—and why each ingredient is necessary.
Vaccines contain several types of ingredients beyond the active antigen (the component that trains the immune system). Each ingredient serves a specific purpose in ensuring the vaccine is safe, effective, and stable. Understanding these ingredients helps address common questions and concerns.
Substances that enhance the immune response to the vaccine antigen. Common example: aluminum salts.
Inactive ingredients that help stabilize, preserve, or manufacture the vaccine. Include sugars, proteins, and gelatin.
A mercury-based preservative. Removed from childhood vaccines since 2001. Still used in some multi-dose flu vaccines.