Vaccine ingredients are thoroughly tested to ensure they are safe for human use. Common components include antigens, adjuvants, preservatives, and stabilizers. While some ingredients, such as aluminum salts and thimerosal (a mercury-based preservative), have raised concerns, extensive research and regulatory reviews have consistently shown that these components are safe at the levels used in vaccines. Misunderstandings about the toxicity of these ingredients often arise from a lack of understanding of dose-response relationships, wherein toxicity is heavily dependent on the dose.
