Correcting this week’s misinformation: week of May 28 2026

Recent news reports that GAVI, the charity that provides vaccines to people around the world, is eliminating vaccines with thimerosal (mercury) due to U.S. demands. So are thimerosal-containing vaccines dangerous?

Thimerosal is a mercury-based ingredient used in some vaccines to help stop bacteria and fungi from growing in multi-dose vaccine vials. Multi-dose vials are used for more than one shot, so they need extra protection from contamination.

In the United States, most vaccines come in single-dose vials. Because of this, most vaccines do not contain thimerosal. One exception can be some multi-dose flu vaccines. In lower-income areas, especially places where it is hard to keep vaccines cold, thimerosal may still be used to help keep vaccines safe.

Some people worry about thimerosal because it contains mercury. But not all types of mercury are the same. Thimerosal contains ethylmercury, which leaves the body quickly. This is different from methylmercury, the type of mercury found in some fish that can build up in the body over time.

Thimerosal has been used in vaccines, medicines, and contact lens solutions since the 1930s. Studies of babies, including premature and low-birth-weight babies, show that ethylmercury leaves the body quickly. About half of it is gone in three to seven days, and the rest leaves the body in stool. Within about a month after vaccination, mercury levels in the blood return to normal.

Research has also shown that thimerosal does not increase the risk of autism and does not harm the brain or body. Thimerosal was removed from most childhood vaccines in the United States in 2001, but autism diagnoses continued to rise after that. This is one reason scientists say thimerosal is not the cause of autism.

Gavi is working to remove thimerosal from vaccines, but NOT because thimerosal is dangerous. Instead, the decision is connected to funding concerns. Gavi’s goal is to keep vaccines available in countries that need them, especially where dangerous infectious diseases are still a major threat.

Even though he received a letter from the FDA explaining that no deaths in children were definitively linked to COVID vaccines, Wisconsin Senator Ron Johnson is still saying that 39,000 children died because of the COVID vaccine.

Senator Johnson’s claims about vaccine safety use VAERS data. VAERS stands for the Vaccine Adverse Event Reporting System. It is a tool used to collect reports about health problems that happen after vaccination.

VAERS is an early warning system. Anyone can submit a report about anything that happened to them after they were vaccinated. This means it helps experts notice possible safety concerns. But VAERS reports do not prove that a vaccine caused a health problem or death. The VAERS system itself explains that its data should not be used alone to decide cause and effect.

If VAERS shows a higher number of certain health problems than expected, experts can study the reports more closely. They can look at individual cases, compare them with other data, and do more research to see if there may be a real connection.

During the pandemic, under the Emergency Use Authorization (EUA), every death that occurred after vaccination was supposed to be reported to VAERS, whether or not the vaccine caused the death. This means deaths from car accidents, other illnesses, suicide, or other causes could be included in VAERS.

Because of this, people cannot look only at the number of deaths reported to VAERS and say the vaccine caused them. More investigation is needed to understand what happened. Using VAERS numbers alone can give a misleading picture.

Brian Hooker claims he interviewed a CDC whistleblower who said they had proof that vaccines cause autism, but they hid it. They used this claim to make the film Vaxxed in 2016.

This interview and the subsequent movie were based on Brian Hooker’s reanalysis of a study that found no link between vaccines and autism. A reanalysis means looking at the data from a study again, but using a different method to see if you get new results.

Hooker’s reanalysis was first published in a medical journal called the Journal of Translational Neurodegeneration. Later, the journal retracted it, saying it should not be trusted. The paper was then published again by another group, the American Association of Physicians and Surgeons. This group is very small and is known for supporting weak or questionable scientific claims.

Experts had problems with Hooker’s work. They said it had serious problems and did not consider other important factors that might affect the results. They also said he used the CDC’s (Centers for Disease Control and Prevention) data in the wrong way and that his overall study design was not appropriate.

One problem was that Hooker used a cohort design, which is a study method where researchers follow groups of people over time to see how different experiences, like getting a vaccine, affect them. The original dataset, however, was meant for a case-control analysis, which compares people who already have a condition (such as autism) with people who don’t to see what may have caused the difference. Because Hooker switched methods, his results were not reliable.

Hooker also divided the data into many smaller groups and tested them again and again. These smaller group tests are called subset analyses. Doing too many subset analyses can lead to false positives, which are results that look like they show a real connection but actually happen just by chance. This problem is often called data dredging, and it makes weak patterns look stronger than they really are.

Hooker’s reanalysis claimed that African-American boys who got the MMR vaccine between ages 24 and 36 months were more likely to be diagnosed with autism. But these children were vaccinated later than usual. It is possible that some of them had already been diagnosed with autism, and they got the vaccine later when their parents enrolled them in early education programs that required children to be vaccinated.

Many large and careful studies do not agree with Hooker’s claim. For example, one in Denmark followed more than 650,000 children. It found that children who got the MMR vaccine were no more likely to have autism than children who did not.

Overall, the best research shows that vaccines do not cause autism. Instead, other studies show that autism is linked to differences in how the brain develops, especially in the prefrontal cortex, the part of the brain that helps with planning, decision-making, and social behavior. These brain changes happen before birth, which means autism starts very early in development and is not caused by vaccines.