Correcting this week’s misinformation: week of May 1, 2025

Correcting this week’s misinformation: week of May 1, 2025

Are vaccines tested and monitored for safety?

The Claim:

On a new episode of Dr. Phil’s primetime TV show, RFK Jr. claims that vaccines aren’t safety tested, were never tested against placebos, that over 99% of vaccine injuries go unreported, that vaccines can cause autism, that the mumps vaccine doesn’t work, and that we don’t really know if vaccines are safe

The Facts:

Robert F. Kennedy Jr. makes several claims about vaccines that sound concerning but are not true. One of his biggest claims is that vaccines were never tested for safety, but that’s simply false. Before any vaccine is approved, it goes through years of safety testing in labs and in clinical trials with real people. These trials include thousands of participants and often compare vaccinated groups to placebo groups or to groups getting other vaccines. For example, the MMR vaccine (for measles, mumps, and rubella) was tested and studied for years before it was licensed, and it’s been used safely for decades since then. Scientists still track vaccine safety after approval using systems like VAERS and the Vaccine Safety Datalink, and researchers constantly update safety info with new data.

Kennedy also says that vaccines were never tested against placebos, but that’s not true either. Many vaccines, including the HPV and rotavirus vaccines, have been studied in large clinical trials that used placebos. These trials help scientists find out exactly what reactions are caused by the vaccine and what might be caused by other factors. Even when vaccines aren’t tested with an inert placebo, they are compared to similar injections to make the studies fair and ethical.

Another wrong claim is that more than 99% of vaccine injuries go unreported. This idea comes from a report, not a “Harvard study,” about using electronic health records to improve reporting to VAERS. The report, which used data from 2007–2010, didn’t explain where the 1% number came from, and it wasn’t based on all kinds of vaccine side effects—just a sample of one hospital system. Since then, VAERS has made it easier to report events online, so the amount of data collected has likely improved. Serious vaccine-related problems are rare, and when they do happen, they’re more likely to be reported than mild ones like a sore arm. https://digital.ahrq.gov/sites/default/files/docs/publication/r18hs017045-lazarus-final-report-2011.pdf

The claim that vaccines cause autism is one of the most dangerous pieces of misinformation. Dozens of studies have shown no link between vaccines and autism. Scientists have studied this for years, looking at hundreds of thousands of kids, and have always found the same result: vaccines don’t cause autism. In fact, researchers now know that autism begins before birth. Brain autopsies show that differences in the brain’s structure and organization begin in the womb, long before any vaccines are given. Genes and early brain development—not vaccines—are responsible.

Kennedy also falsely says that the mumps part of the MMR vaccine doesn’t work. That’s not true. The MMR vaccine is about 88% effective at preventing mumps after two doses. It has greatly reduced the number of people who get mumps, and even if someone who got the vaccine does get sick, they usually have a milder illness. Without the vaccine, mumps used to cause painful swelling, hearing loss, and even infertility in some people.

Finally, the idea that we don’t really know if vaccines are safe just doesn’t match reality. Vaccines are among the most studied medical products ever made. They are tested before they are approved and monitored for years afterward. Scientists around the world keep checking safety data, and they are quick to act if they find problems. Thanks to vaccines, we have wiped out smallpox, nearly eliminated polio, and saved millions of lives from deadly diseases like measles, whooping cough, and meningitis.

When people repeat these false claims, they scare parents and put public health at risk. Instead of guessing or trusting rumors, it’s better to ask real experts, read good science, and remember that vaccines are one of the most important ways we protect ourselves and our communities.

Sources:

Did the CDC hide proof that vaccines cause autism?

The Claim:

An old clip from the movie Vaxxed claims that a CDC scientist admitted the CDC covered up evidence linking the MMR vaccine and thimerosal to autism. And that top CDC officials were involved and later took high-paying jobs at vaccine companies.

The Facts:

This video is part of Andrew Wakefield’s movie based on Brian Hooker’s reanalysis of the work described in the video.

The reanalysis was published in the Journal of Translational Neurodegeneration, and then–notably–retracted. The new publishing journal is an arm of the American Association of Physicians and Surgeons–a small group that makes spurious positions.

The original publication was part of an anti-vaccine publicity campaign by the defrocked doctor Andrew Wakefield, which included his controversial film VAXXED.

Experts criticized Hooker’s re-analysis, saying it was flawed and didn’t consider other variables that could influence the results. They questioned how he used the CDC data set and argued that the study design was inappropriate for his analysis.

Brian Hooker used a cohort design to analyze a dataset originally intended for case-control analysis. Subsequently, he performed multiple subset analyses, which can be susceptible to false positives.

When evidence is excessively segmented or divided into smaller subsets for analysis, there is a higher likelihood of observing apparent correlations that may not actually be meaningful or valid. This phenomenon is often called the “multiple comparisons problem” or “data dredging.”

Hooker’s reanalysis concludes that African-American males who receive the MMR between ages 24 months and 36 months were more likely to the diagnosed with autism. These were children who received the vaccine late. It is possible that they received the vaccine after diagnosis and when their parents were seeking early childhood special education services which may have required immunization.

Are mRNA vaccines uncontrollable?

The Claim:

In a widely circulated video, National Institutes of Health director Dr. Jay Bhattacharya claims that COVID vaccine use has dropped because mRNA vaccines are unsafe and unreliable, since scientists can’t fully control how much antigen is made, where it goes in the body, or whether the right proteins are produced.

The Facts:

mRNA vaccines, like the ones made for COVID-19, work by giving the body a tiny set of instructions. These instructions tell your cells to make a harmless piece of the virus, usually the spike protein. This protein cannot cause COVID-19, but it teaches your immune system what the real virus looks like. Once your body recognizes it, your immune system learns to fight it off if you ever come into contact with the real virus. After the protein is made, your body quickly gets rid of the mRNA instructions, usually within a few days. Scientists have studied this process very carefully, and they have shown that it works the way it is supposed to without causing the body to lose control or make dangerous mistakes.

The claim that scientists cannot control the amount of antigen (the spike protein) made by your cells is misleading. The amount of mRNA given in each vaccine dose is very carefully measured. Clinical trials and studies after the vaccines were released have shown that the immune response is consistent across millions of people. While it is true that different people’s bodies can react slightly differently (like some people having a sore arm and others not), that is normal for all vaccines and even for regular infections. There is no evidence that the mRNA vaccines cause dangerously large or uncontrolled production of spike protein.

The idea that the spike protein could go “anywhere” in the body in dangerous ways is also not supported by science. Studies have shown that most of the mRNA stays near the injection site, usually the muscle in your upper arm, and nearby lymph nodes. These are exactly the places where your immune system needs to be activated. The body is very good at breaking down the mRNA quickly, and your immune system destroys the spike protein itself after it does its job of teaching. There is no evidence from millions of vaccine doses that the spike protein travels around the body, causing harm.

Another false claim is that the body often makes the wrong proteins from the mRNA vaccines. Scientists designed the mRNA very carefully so that it would be copied correctly. There is some natural variation anytime your body makes proteins, but this is very small and not harmful. If serious errors happened often, we would have seen major problems in the tens of millions of people who got vaccinated. Instead, what we saw was that vaccinated people were much less likely to get very sick, go to the hospital, or die from COVID-19.

Finally, the scientists who developed the mRNA technology indeed won a Nobel Prize, but that doesn’t mean the technology is unfinished or unsafe. It means their discovery was important and helped save millions of lives. Scientists will keep improving vaccines in the future, just like they always have with every kind of medicine. However, the COVID-19 mRNA vaccines are already very effective and safe, as shown by many studies around the world.

Sources:

Disclaimer: Science is always evolving and our understanding of these topics may have evolved too since this was originally posted. Be sure to check out our most recent posts and browse the latest Just the Facts Topics for the latest.

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