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Why is ethyl-mercury in some multi-dose flu vaccines?

Experts say it’s not a health concern.


Flu season is fast approaching and when it comes to flu vaccines, there’s a lot of misinformation out there. 

According to the Centers for Disease Control and Prevention (CDC), many vaccines, including the flu vaccine come in a small bottle with more than one dose of vaccine. They’re called multi-dose vials, and they’re accessed multiple times to vaccinate many people with a fresh needle and syringe every time. 


Does the flu vaccine have mercury in it? If so, why? 


This is true.

Yes, there is a small amount of ethyl-mercury added to the multi-dose flu vaccines to keep them from contamination. But, the experts say it’s not a health concern. 



According to the CDC, multi-dose vials of the flu vaccine contain thimerosal, an ethyl-mercury-based preservative that’s been used in some vaccines since the 1930s. It’s used to prevent bacteria and germs from contaminating vaccines. 

The CDC said thimerosal leaves your body quickly and doesn’t build up and reach harmful levels. It said most single-dose vialspre-filled syringes of the flu shot, and the nasal spray flu vaccine do not contain a preservative because they are intended to be used once.

Each vial only has a trace amount of ethyl-mercury, 25 micrograms, that's about the same amount in a three-ounce can of tuna fish according to the FDA. 

The FDA is working to reduce or remove thimerosal from all existing vaccines. The agency is working with manufacturers, particularly those that manufacture childhood vaccines, to reach the goal of eliminating thimerosal from vaccines, and has been collaborating with other PHS agencies to further evaluate the potential health effects of thimerosal.

All vaccines routinely recommended for children six years of age or younger and marketed in the U.S. contain no thimerosal or only trace amounts (1 microgram or less mercury per dose), with the exception of inactivated influenza vaccine, which was first recommended by the Advisory Committee on Immunization Practices in 2004 for routine use in children six to 23 months of age.

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