No link between MMR vaccine and autism, despite researcher's arrest

"Vaccines. Autism FRAUD. The 'science' they used to silence us moms? Built on a criminal," says a September 16, 2025 post on Instagram.

Another Instagram post mentioning Thorsen's arrest says: "Yes, one of the key authors of the research used to shut down the vaccine-autism debate has been accused of massive fraud. How much more autism research is tainted?" It concludes: "The science is NOT settled!"

Similar claims spread on Facebook in French and Spanish.

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Screenshot of an Instagram post taken September 24, 2025

Image

Screenshot of an Instagram post taken September 24, 2025

In April 2011, Thorsen was indicted on 22 counts of wire fraud and money laundering. United States Attorney Sally Quillian Yates said at the time that he was "alleged to have orchestrated a scheme to steal over $1 million in CDC grant money earmarked for autism research" (archived here).

He was arrested June 4, 2025 in Germany, and the United States is seeking his extradition, according to a notice from the US Department of Health and Human Services (HHS) Office of Inspector General (archived here).

The recent social media attention to Thorsen came following a September 15 Breitbart news article resurfacing news of his arrest.

The posts single out a 2002 article published in the New England Journal of Medicine titled: "A Population Based Study of Measles, Mumps, and Rubella Vaccination and Autism." In it, the paper's authors concluded: "This study provides strong evidence against the hypothesis that MMR vaccination causes autism."

But despite the claims online, the lead author, the journal that published the study, and an independent expert all told AFP the alleged financial crimes committed by Thorsen do not negate the findings of the Danish research paper.

"The research idea and concept were mine," Kreesten Madsen, the study's lead author, told AFP in a September 19 email (archived here). "Acquisition, first analysis, and interpretation of the data was done without Poul Thorsen."

Madsen said Thorsen was not central to the project and never had access to its data, but did provide a connection to the CDC, one of several funders for the work.

He said he has "full confidence" in the article as it was written and welcomes others to repeat the study with an even larger dataset.

The New England Journal of Medicine (NEJM) also said it did not find any issues with the paper, despite Thorsen's indictment.

"The study's findings remain valid and are consistent with extensive subsequent research showing no link between MMR vaccination and autism," a spokesperson for NEJM said in a September 20 email.

Similarly, David Mandell, director of the Penn Center for Mental Health at the University of Pennsylvania School of Medicine, told AFP he reviewed the paper's methodology (archived here).

"The methods are highly consistent with what we think about as high-quality science," he said September 22.

"So yes, bring him to justice for stealing grant money from the CDC. But let's not confuse that with the validity of the science that this group and many other groups have done."

No link between vaccines and ASD

HHS defines Autism Spectrum Disorder (ASD) as a developmental disability.

"ASD affects how people interact with others, communicate, learn, and behave. ASD is called a 'spectrum' disorder because people experience different types of symptoms," the agency says on its website (archived here).

Health Secretary Robert F. Kennedy Jr., who has a long history of spreading misinformation about vaccines, has said the United States is facing an ASD "epidemic" and promised to reveal new research into the causes and treatments for the condition.

On September 22, he joined Donald Trump at the White House to announce guidance for doctors and patients, but the press conference quickly veered from the facts as the president vehemently insisted there is a clear link between the use of Tylenol during pregnancy and autism (archived here).

Trump also urged parents to reject the MMR shot in favor of vaccines for a single virus, a proposal that would be a major change to the current recommendations (archived here).

The World Health Organization said September 23 that neither acetaminophen -- the primary ingredient in Tylenol, known as paracetamol in Europe -- nor vaccines have been shown to cause autism.

Longstanding misinformation about the link between the MMR vaccine and autism largely stems from a 1998 paper by Andrew Wakefield, who was struck off as a doctor in the United Kingdom in 2010 (archived here). The Lancet also retracted the study after falsified data was found (archived here and here). 

Research that followed both Wakefield's flawed paper and the work of the Danish team has found no association between vaccination and autism:

• In 2009, researchers from the Children's Hospital of Philadelphia examined seven studies looking at a possible association between autism and thimerosal, a mercury-based preservative in vaccines. All of them failed to support the link (archived here).
• A 2013 CDC study found that the amount of antigens -- substances that trigger the body's immune response and can be included in vaccines in weakened or inactive forms -- received during the first two years of life did not increase a child's risk of developing autism (archived here).

"All the research we have done to date suggests that the causes of autism are primarily genetic," University of Pennsylvania's Mandell said.

"We have looked at whether children got vaccinated. We have looked at when they got vaccinated. We have looked at which combinations of vaccines they've gotten. And in all those studies that were well done, we see no association between vaccines and autism."

The Coalition of Autism Scientists and the Autism Science Foundation echoed this understanding in statements (archived here and here).

Read more of AFP's reporting on vaccine misinformation here.