Is thimerosal in flu shots dangerous?

Claims about thimerosal, including its mythological connection to autism, are gaining new life because of an announced vote regarding thimerosal in influenza vaccines during the ACIP meeting.

We know a lot now about thimerosal. Thimerosal, a mercury compound used today in some flu vaccines, has caused concern due to its name being confused with a harmful type of mercury. Thimerosal contains ethylmercury, which is safe and quickly leaves the body. It’s different from harmful methylmercury found in some fish. Thimerosal has been used safely in vaccines, drugs, and contact solutions since the 1930s. Nowadays, most vaccines use single-use vials, and thimerosal-free vaccines are available for those still concerned.

To drum up concerns, vaccine opponents have to travel back in time and make dull government meetings look nefarious. Such is the case with Simpsonwood.

The 2000 Simpsonwood CDC conference was a two-day meeting organized by the CDC to discuss data from the Vaccine Safety Datalink regarding the possible link between the mercury compound thimerosal in vaccines and neurological issues in vaccinated children. Attendees included experts in various fields, public health organizations, and pharmaceutical companies.

The conference gained notoriety in the anti-vaccination movement when RFK Jr. wrote an article in 2005 alleging a conspiracy to withhold vaccine safety information. However, the article contained numerous factual errors, leading to its retraction.

In 2007, the Senate HELP Committee reviewed the allegations against the CDC and found them to have little merit. The committee found that the CDC did not interfere with vaccine safety studies, and the review groups did not rely on manipulated studies.

Studies show that thimerosal does not increase the risk of autism. In addition, thimerosal has not even been used in childhood vaccines since 2001.

Finally, autism diagnoses continued to rise following the 2001 removal of thimerosal from all childhood vaccines. The continued rise of autism diagnoses is, in fact, mostly due to growing awareness and changing diagnostic criteria.

Autism is linked to genetics and prenatal development, not vaccines. Studies show that if one identical twin has autism, there is a high chance the other twin will, too, even if they were never vaccinated. Research also shows that brain differences in autistic children start developing before birth, long before any vaccines are given. Scientists have studied many possible causes, and vaccines are not a possible cause.