What is the purpose of thimerosal in vaccines?

Thimerosal's primary purpose in vaccines is to prevent contamination. This compound acts as a preservative, particularly in multi-dose vials, by helping to inhibit the growth of bacteria and fungi that could lead to contamination. Preventing contamination is crucial to maintaining the safety and efficacy of the vaccine, as any microbial growth within the vaccine could jeopardize the health of the individuals receiving the vaccine.

While thimerosal may influence some properties related to vaccines, such as stability and concentration, its role as a preservative directly addresses the need to protect vaccines from microbial contamination. This is especially important in the context of multi-dose vaccines, where exposure to the environment increases the risk of contamination each time the vial is accessed.