Is there mercury in a flu shot?

Answer 1

Yes, but only tiny traces. The 2011-2012 flu season vaccine is made exactly like flu vaccines have been made for decades (including thimerosal) with an extremely high safety record even compared to other vaccines. The minuscule amount of Mercury from the thimerosal preservative used in some doses of influenza vaccine may leave traces present in your body for a very short time. Single dose vials of the flu vaccines have no thimerosal in them, therefore no mercury, but may need to be special ordered in advance by your pharmacy or doctor, which may in turn raise the cost.

However, to put this in perspective, the amount of mercury from that compound in the flu vaccine when used, is approximately 24.5 mcg of mercury per dose of vaccine. This is well below the amount of mercury that a single serving of fish in your diet might contain.

Fish that are known to contain low amounts of mercury include catfish. It has been determined that for the amount of mercury in catfish to pose any potential danger, these hypothetical health risks from the mercury in catfish would only begin at a weekly intake of 342.8 ounces (21.4 pounds) of the fish. This should put into perspective the insignificance of the mercury from a flu shot. Scientific studies have proven no connection between thimerosal and untoward health consequences from vaccine use.

The following is quoted from the Centers for Disease Control and Prevention (CDC) website:

What is thimerosal?

Thimerosal is a very effective preservative that has been used since the 1930s to prevent contamination in some multi-dose vials of vaccines (preservatives are not required for vaccines in single dose vials). Thimerosal contains approximately 49% ethylmercury. There is no convincing evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999 the Public Health Service (PHS) agencies, the American Academy of Pediatrics (AAP), and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure.

Today, all routinely recommended licensed pediatric vaccines that are currently being manufactured for the U.S. market, with the exception of influenza vaccine, contain no thimerosal or only trace amounts. Thimerosal preservative-free influenza vaccines are available, but in limited quantities. The total amount of inactivated influenza vaccine available without thimerosal as a preservative will continue to increase as manufacturing capabilities are expanded.

Does the influenza vaccine contain thimerosal?

Yes, the majority of influenza vaccines distributed in the United States currently contain thimerosal as a preservative. However, some contain only trace amounts of thimerosal and are considered by the Food and Drug Administration (FDA) to be preservative-free. Manufacturers of preservative-free flu vaccine use thimerosal early in the manufacturing process. The thimerosal gets diluted as the vaccine goes through the steps in processing. By the end of the manufacturing process there is not enough thimerosal left in the vaccine to act as a preservative and the vaccine is labeled "preservative-free".

Is it safe for children to receive an influenza vaccine that contains thimerosal?

Yes. There is no convincing evidence of harm caused by the small amount of thimerosal in vaccines, except for minor effects like swelling and redness at the injection site due to sensitivity to thimerosal. Most importantly, since 1999, newly formulated thimerosal preservative-free childhood vaccines (Hepatitis B, Hib, and DTaP) have been licensed. With the newly formulated childhood vaccines, the maximum total exposure during the first six months of life will now be less than three micrograms of mercury. Based on guidelines established by the FDA, the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR), no child will receive excessive mercury from childhood vaccines regardless of whether or not their flu shot contains thimerosal as a preservative.

Rsearch suggests that healthy children under the age of 2 are more likely than older children and as likely as people over the age of 65 to be hospitalized with flu complications. In addition, children between 24-59 months of age have higher rates of influenza-related doctor and Emergency Department visits than older children. Therefore, vaccination with either reduced or standard thimerosal-content flu vaccine is recommended for children between the ages of 6 and 59 months by CDC's Advisory Committee on Immunization Practices.

Is it safe for pregnant women to receive an influenza vaccine that contains thimerosal?

Yes. A study of influenza vaccination examining over 2,000 pregnant women demonstrated no adverse fetal effects associated with influenza vaccine. Case reports and limited studies indicate that pregnancy can increase the risk for serious medical complications of influenza. One study found that out of every 10,000 women in their third trimester of pregnancy during an average flu season, 25 will be hospitalized for flu related complications.

Additionally, influenza-associated excess deaths among pregnant women have been documented during influenza pandemics. Because pregnant women are at increased risk for influenza-related complications and because a substantial safety margin has been incorporated into the health guidance values for organic mercury exposure, the benefits of influenza vaccine with reduced or standard thimerosal content outweighs the theoretical risk, if any, of thimerosal.

Some types do, although it is a very scant amount. Multi-dose vials of vaccines for some types of flu must have preservatives added and usually the one used is thimerosal. Thimerosal contains trace amounts of mercury. However, to put it in perspective, it is no more than the amount of mercury you would get when eating a single meal of fish. It has been proven safe for use as the preservative over decades of use in flu shots. If you are concerned, you can ask for vaccination with a single dose vial or pre-filled single dose syringe which do not contain the preservatives, however, these are not always available and you would need to plan in advance to find single dose preparations.