Is autism a result of too many vaccines?

On Monday, President Trump signed a new Executive Order about childhood vaccines. It suggests a vaccine schedule more like Denmark’s, which protects against 11 diseases instead of 17. It would also spread vaccines out over more doctor visits and separate some combination vaccines, like MMR.

At the signing, Trump, RFK Jr., and Stephen Miller said they were concerned that vaccines might cause autism.

• The childhood vaccine schedule is carefully studied and updated over time.
• Vaccines do not cause autism.
• Autism has other known risk factors and early developmental roots.

The AAP childhood vaccine schedule did not appear all at once. It grew slowly as scientists developed new vaccines to prevent more diseases. Three times a year, experts would review the latest research and decide which vaccines children need and when they should get them. Vaccines are tested before they are approved, and their safety continues to be watched after they are in use.

The schedule is designed to protect children when they need protection most. Combination vaccines make this easier by protecting against several diseases with fewer shots. Fewer shots can mean less stress for children and families and can make it easier to stay on schedule. Getting vaccines on time also helps protect children from serious diseases and reduces the chance that those diseases will spread in families, schools, and communities. The American Academy of Pediatrics recommends a schedule designed to protect children at the ages when they are most at risk.

Some people worry that children get “too many” vaccine ingredients at once. But today’s vaccines contain far fewer antigens, the parts that train the immune system, than vaccines did decades ago. Better technology has helped vaccines to protect against more diseases with fewer antigens.

Aluminum is another vaccine ingredient that can cause concern. Aluminum salts have been used in some vaccines for many decades to help the immune system respond. The amount is small, and people are also exposed to aluminum through food and water. Aluminum salts are used in vaccines and have a long safety record. A 2025 study of more than 1.2 million children found no increased risk of autism or dozens of other chronic health problems linked with greater exposure to aluminum from vaccines.

Scientists have spent decades studying whether vaccines cause autism. They have looked at the MMR vaccine, vaccine ingredients, and overall vaccine exposure. A large meta-analysis involving more than 1.2 million children found no link between vaccines and autism. A 2026 study of more than 2.5 million U.S. children also found no increased risk of autism after MMR vaccination.

Scientists are also learning more about what plays a role in autism. Genetics is one of the strongest known factors, and research suggests that differences linked with autism can begin while the brain is developing before birth. Factors such as premature birth and older parental age have also been linked with autism.

More people are being diagnosed with autism today, but that does not mean vaccines caused the increase. Greater awareness, better screening, and changes in how autism is diagnosed have helped more people get identified. The AAP explains some of the reasons autism diagnoses have increased. Researchers are still studying autism so we can better understand its causes and improve care and support for autistic people and their families. Research dollars can help answer those open questions instead of repeatedly testing vaccine claims that large studies have already examined.

The new federal vaccine recommendations could also change what families hear about at doctor visits. Some vaccines that were routinely recommended are now listed for shared decision-making or for certain higher-risk groups. Families can still ask about these vaccines. Parents and caregivers may want to ask their child’s doctor which vaccines are available and which vaccines the American Academy of Pediatrics recommends for their child.