Flu season has begun, and if you have not already gotten your flu shot, it’s time to start thinking about it.

There’s been recent talk on social media about mercury being in flu vaccines. Some people believe mercury in flu shots could be linked to autism.

Both the Centers for Disease and Control as well the Food and Drug Administration confirmed there is a preservative added to vaccines that is 50 percent mercury.

The mercury-containing organic compound is called Thimerosal. FDA spokeswoman Lyndsay Meyer told WUSA9 “Seasonal influenza vaccines in a multi-dose presentation contain thimerosal as a preservative. However, FDA-approved seasonal influenza vaccines are available in single-dose presentations that do not contain thimerosal for use in infants, children, adults, the elderly and pregnant women.”

The CDC says they've done numerous studies that show it doesn't have a link to autism. It's added to the vaccine to stop bacteria and fungus from growing in the vial causing a staph infection.

Meyer also says Thimerasol is used only in multi-dose shots where the physician needs to refill the syringe multiple times.

Each vial has only trace amounts of mercury -- 25 micrograms, which is about the same amount in a three-ounce can of tuna fish, according to the FDA.

Thimerosal does not cause autism, according the American Academy of Pediatrics.

“A large body of scientific evidence demonstrates that thimerosal-containing vaccines are not associated with increased risk of autism spectrum disorders in children. Thimerosal from vaccines has not been linked to any medical condition," according to AAP's Recommendations for Prevention and Control of Influenza in Children, 2017-2018.

The FDA has a list of approved mercury-free vaccines. To learn more, click here.

VERIFY: Sources

Food and Drug Administration

Centers for Disease and Control

Environmental Protection Agency

American Academy of Pediatrics

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