Vaccinations

Vaccine Safety: Examine the Evidence

Vaccines are under constant study. For a vaccine to be recommended—as part of the childhood and adolescent immunization schedule—it must be tested, found safe and closely monitored. Safety testing begins as soon as a new vaccine is made and clinical trials begin, and evidence of safety is gathered for as long as it is in use.

The truth about vaccines & autism

The U.S. Centers for Disease Control and Prevention (CDC) recently added misleading claims to its autism webpage. 11/20/2025.

We want to be clear: decades of high-quality, large-scale studies show that vaccines do not cause autism. "Parents deserve peace of mind. Decades of rigorous research have shown vaccines do not cause autism," said Dr. Susan Kressly, president of the American Academy of Pediatrics. "Vaccines are one of the safest and most effective ways to protect children’s health and help them thrive."

What to know about vaccines

The child and adolescent immunization schedule is a policy that is recommended by the American Academy of Pediatrics (AAP). Like all AAP policies, it is developed based on expert review of all available evidence.

As a parent, you can be reassured to know that there have been hundreds of large-scale studies around the world on vaccine safety during the past few decades. They demonstrate that:

Recommended vaccines are safe for children and teens.
Vaccines are not associated with conditions like diabetes or problems with fertility.
Vaccines are not associated with autism or developmental delay.
Measles-containing vaccines are safe.
Vaccine ingredients are safe.

Research continues to confirm that vaccines are safe and effective—and they protect children and teens from serious diseases.

Evidence Snapshot

Immunizations have dramatically reduced the incidence of vaccine-preventable diseases. The AAP rigorously reviews  vaccine safety and effectiveness data. The current U.S. childhood and adolescent immunization schedules are based on research showing when vaccines work the best to support children’s and adolescents’ immune systems.  

Professionals like pediatricians identify autism by carefully reviewing a child’s medical, social, family and developmental histories along with directly observing the child’s behaviors. Autism is often first identified in children between 12 and 24 months. This corresponds to many developmental milestones and temporally corresponds to key childhood vaccines giving some the false impression of a linkage between autism and vaccines. 

How we know that vaccines are safe & effective for children & teens

Here's a round-up of some of the studies published in science publications so parents to read the evidence for yourself.

Note: This is not an exhaustive list—vaccine safety studies are constantly being conducted and published and may not be reflected here. Experts closely evaluated the methods and data analyses that produced the results described before accepting these studies for publication in scientific journals.

Agency for Healthcare Research and Quality (AHRQ) Publication No. 21-EHC024 (2021)

Vaccines Are Not Associated With Autism: An Evidence-Based Meta-Analysis of Case-Control and Cohort Studies

Taylor L, et al. Vaccine. 2014;32:3623-3629

Increasing Exposure to Antibody-Stimulating Proteins and Polysaccharides in Vaccines is Not Associated with Risk of Autism

DeStefano F, et al. J Peds. 2013;163:561-567

On-time Vaccine Receipt in the First Year Does Not Adversely Affect Neuropsychological Outcomes

Smith M, Woods C. Pediatrics. 2010;125:1134-1141

Autism Occurrence by MMR Vaccine Status Among U.S. Children With Older Siblings With and Without Autism

Jain A, et al. JAMA. 2015;313:1534-1540

There are many more studies availible for more vaccines to see the full list please go to https://www.healthychildren.org/English/safety-prevention/immunizations

Main Points

Since the prior 2014 Agency for Healthcare Research and Quality (AHRQ) report on vaccine safety, found no new evidence of increased risk for key adverse events following administration of vaccines that are routinely recommended for adults, children, and pregnant women.
Signals from the prior report remain unchanged for adverse events that include anaphylaxis in adults and children, and febrile seizures and idiopathic thrombocytopenic purpura in children. There continues to be no evidence of increased risk of adverse events for vaccines currently recommended in pregnant women.
There remains insufficient evidence to draw conclusions about some rare potential adverse events.

World Health Organization statement on autism-related issues

The World Health Organization (WHO) emphasizes that there is currently no conclusive scientific evidence confirming a possible link between autism and use of acetaminophen (also known as paracetamol) during pregnancy.

Also, a robust, extensive evidence base exists showing childhood vaccines do not cause autism. Large, high-quality  studies from many countries have all reached the same conclusion. Original studies suggesting a link were flawed and have been discredited. Since 1999, independent experts advising WHO have repeatedly confirmed that vaccines—including those with thiomersal or aluminum—do not cause autism or other developmental disorders.  

https://www.who.int/news/item/24-09-2025-who-statement-on-autism-related-issues