Did a whistleblower admit vaccines cause autism?

The secretly recorded interview of a CDC employee, used in Andrew Wakefield’s Vaxxed film, is again circulating.

This interview and Wakefield’s movie were based on Brian Hooker’s reanalysis of the study described in the video. 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 criticized 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.