What is Thimérosal and why RFK Jr. says it is dangerous?

ahsan65@gmail.comJune 27, 2025

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What is Thimérosal and why RFK Jr. says it is dangerous?

An important advisory committee with the federal government voted this week to withdraw its support from the flu plans containing the conservative Thimérosal.

The Consultative Committee for Vaccination Practices (APIP) guides the recommendations of the vaccines of centers for Disease Control and Prevention (CDC). Earlier this month, the Secretary of Health, Robert F. Kennedy Jr., dismissed the 17 members of the Committee and appointed eight new members, some of whom have a history of complaints on vaccines which are not safeguarded by scientific research, as reported by NPR.

Kennedy himself specifically criticized the Thimérosal; He wrote a book published in 2014 which called for the prohibition of the Thimérosal in vaccines due to an alleged autistic link.

However, multiple research studies have shown that any concern that Thimérosal causes autism is not founded.

Thimérosal is only present in a small number of flu vaccines. During the 2024-2025 flu season, 96% of flu vaccines administered in the United States were free from Thimérosal, according to AP reports.

What is Thimérosal?

Thimérosal is a mercury preservative used in drugs or vaccines that come to bottles with more than one dose.

Pharmaceutical companies have used Thimérosal in vaccines since the 1930s.

“We use it in bottles intended to be used on several patients to prevent growth in case certain bacteria will be accidentally introduced,” explains Brian Labus, PHD, MPH, an epidemiologist of infectious diseases and assistant professor at the University of Nevada, Las Vegas School of Public Health. This can happen, for example, if there are bacteria on syringe needles inserted in a bottle.

Is Thimérosal sure?

Many studies support the safety of vaccines containing Thimérosal, according to the US Food and Drug Administration (FDA). Only minor reactions, such as redness or swelling on the injection site, have been reported.

“It has been around for a long time, and that’s for sure,” explains Thomas Russo, MD, professor and infectious diseases at the University of Buffalo Jacobs School of Medicine and Biomedical Sciences.

However, people can see that Thimérosal is made from mercury and is “a little panicked”, he admits.

At high levels, methylmercure (the type found in some fish) can be toxic. But thimérosal contains ethylmercure, which the body breaks down and erases much more quickly than methylmercury.

In addition, “the amount contained in these vaccines is tiny compared to the exposure we obtain from these compounds in daily life and the things we ingest,” explains Dr. Russo.

For example, “you are exposed to more mercury by eating a tuna sandwich that you get a vaccine,” said Dr. Labus.

Several studies have failed to identify the potential links between Thimérosal and Autism, including CDC research published in 2010.

Very few vaccines contain thimérosal

Even if there is no evidence that the small quantity of Thimérosal in vaccines is dangerous or causes autism in 1999, the public health service (including the FDA, the CDC and the National Institutes of Health), the American Academy of Pediatrics, the American Academy of Family Physicians and the manufacturers of vaccines have agreed to reduce or eliminate Vaccines for children for children.

The use of the curator has also decreased in vaccines overall, as manufacturers have reformulated vaccines and developed more doses for single use.

“The only flu vaccines containing thimerosal are those in bottles for several adult patients,” explains Labus. “The doses of influenza packed individually do not contain it, and no pediatric vaccine.”

These days, most people receive vaccines against unique dose flu, says Russo.

Attacks against Thimérosal could undermine confidence in all vaccines

Since the Thimérosal is only found in a small number of flu vaccines, Russo affirms that the ACIP’s decision will probably not have much impact on the landscape of vaccines. This does not mean either that the conservative is not sure, he says.

But he fears that this decision can “undermine, in the American public, the view of the security of vaccines”.

Labus agrees. “The committee’s anti-Vaxxers deploy the greatest successes of their disinformation campaigns to try to frighten people to be vaccinated,” he said. He says that the committee’s decision has “absolutely no basis in rational and scientific thought”.

In the United States, vaccines are “extremely well approved” and safely, Russo underlines, and everyone should still get a flu vaccine.

“The advantages of vaccines approved in this country prevail from afar on the potential negative effects,” he said.