Thimerosal in Flu Vaccine (original) (raw)
- Thimerosal is an ethyl mercury-based preservative used in vials that contain more than one dose of a vaccine (multi-dose vials) to prevent germs, bacteria and/or fungi from contaminating the vaccine.
Thimerosal in vaccines
Flu vaccines in multi-dose vials contain thimerosal to safeguard against contamination of the vial. Most single-dose vials and pre-filled syringes of flu shot and the nasal spray flu vaccine do not contain a preservative because they are intended to be used once.
Preservatives sometimes used in vaccines
Preservatives are used to protect vaccines packaged in multi-dose vials. Each time a vaccine dose is drawn from a multi-dose vial, bacteria or fungi can enter the vial. Receiving a vaccine contaminated with bacteria or fungi can be dangerous. Preservatives are needed to prevent contamination of multi-dose vials each time individual doses are drawn.
Thimerosal use in vaccines and other medical products has a record of being very safe. Data from many studies show no evidence of harm caused by the low doses of thimerosal in vaccines.
Learn more about thimerosal
Answers to common questions about vaccine safety and thimerosal.
July 31, 2024
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