“Awareness needs to be more than numbers from the CDC and scare tactics and conversations about vaccines. It needs to be more than spreading generalizations about some traits that occur in some people with autism. There needs to be a component of compassion. While people are being made aware, maybe they could be reminded to be kind and giving and compassionate? Perhaps the awareness we need to focus on is our own awareness of our actions toward those around us who are different than we are.”

– Mother of an autistic son

With that in mind, let’s talk about autism and vaccines. Of all the topics related to vaccines, this may be the most difficult. Difficult because there are still many unknowns about Autism Spectrum Disorder (ASD) and because of the impact of emotional stories we have heard, both on the internet and within our social groups. We now have a greater confidence in the influence of genetics on autism, but much about epigenetics and the environment as it relates to autism remains unknown. This information is for parents who find that there is so much contradictory information on the internet it seems impossible to sift through. We offer a few basic facts about the controversy between autism and vaccines.

No matter your views on this subject, we ask that you seek out scientific, evidenced-based studies in making your decision to vaccinate or not. Stories passed on by friends, family, or the internet are not exactly scientific research despite the strong emotional effect they have upon us.

So, here we go, the million dollar question: Do vaccines cause autism?

No, they do not.

So why does this continue to be an issue? After all the scientific evidence to the contrary, why are we still talking about autism and vaccines in the same sentence?

Basic Overview of Autism

The term Autism Spectrum Disorder (ASD) is a large umbrella term that includes several different disorders, all of which have in common abnormal development of communication skills, social skills, and repetitive or obsessive traits (Brown).

While children are often diagnosed between the ages of 18 months and 2 years-when language development should be at its peak-there are usually indications that a child has autism prior to the time a child is 1 year old.

Some children with autism will develop normally and then regress or appear to regress, while other children, such as those with Asperger’s Syndrome, may reach school age prior to a diagnosis.

Language Development

“There is a growing research in language development that looks at brain anatomy. Primitive brain parts control early language development from birth to 18 months. At 18 to 24 months, the mature brain parts turn on and language takes off. With autistic children, mature language does not take off. But from a parent’s perspective it may look like a loss of skills.” (Brown)

Current Autism Prevalence

In 2014 the CDC’s Autism and Developmental Disabilities Monitoring Network reported approximately 1 in 59 children in the U.S. is diagnosed with an autism spectrum disorder. The rates for boys and girls differ with 1 in 42 for boys and 1 in 189 for girls. (Autism Science Foundation)

The Autism “Epidemic”

What if we said that the U.S. media has been the driving force behind the idea that there is an out of control autism epidemic? Would you believe us? Here are several reasons why there is probably not an actual significant increase in the incidence (number of cases) of autism.

Before we dive in, it is important to note that current research supports the hypothesis that the reported increased rates of autism do not reflect an actual increase in autism incidence but rather a broadening of the diagnosis. However, it is possible and even probable that there is a small, but true, increase of autism rates that we can’t yet see in the data. It doesn’t mean scientists are denying it, only that it is not yet “statistically significant.” Statistical significance refers to how scientists determine if the outcome of a study is the result of an actual relationship between specific things or merely the result of chance.


To understand better how behavioral health diseases are diagnosed, it’s important to understand the Diagnostic and Statistical Manual of Mental Disorders.   Autism was incorporated into DSM-III (the third edition) in 1980. We are now in the fifth edition, DSM-V (2013). Autism is listed under the title Pervasive Developmental Disorders and has been modified in each edition. In DSM-III there were six mandatory criteria with very specific language for diagnosis, but in DSM-IV (1994) there are 16 optional criteria of which only 8 need be met and the language is much looser. Where DSM-III (1980) states “gross deficits in language development, DSM-IV (1994) states one of the options as simply “difficulty sustaining a conversation.”

The newer manuals also incorporate three additional diagnostic categories: Asperger’s, Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS), and Autistic Disorder. Asperger’s and PDDNOS are considered “milder” forms of autism and make up almost three quarters of recent diagnosis.

Diagnosis and Reporting

The diagnosis of autism has only been with us for about 70 years when it was first identified by Leo Kanner. That’s not very long. But most likely, people with autism have always been around. Prior to Kanner’s study, those with autism, depending on the severity, were either not clinically noticed, were referred to as being “off” or “different,” or diagnosed as schizophrenic or insane. Later on some would also fall under the diagnosis of mental retardation. We’ve come a long way in addressing the specific characteristics and needs of autistic children.

The data sets that are frequently used to support the “autism epidemic” argument are often misunderstood or misinterpreted. Take, for example, what is the oft referred to “California Data.” There are many reasons to be cautious with this data. In 2002 the University of California completed their MIND study (The California Data) which had been commissioned by the California legislature. This study rose out of reasonable concern over what appeared to be a 273% increase in rates of autism. Their conclusion was that the broadening of the diagnostic criteria did not impact the rapidly rising rates.

So what was wrong with their study? They studied 2 cohorts of children with autism born in 1983-85 and 1993-95. Both groups were assessed with the same instrument (a data collecting interview), however the instrument was based on the later DSM-IV which hadn’t been around in the early 1980s and was much more inclusive. For that reason, all the children from the first cohort met the criteria as did all the children of the second. The researchers then erroneously concluded broadening the diagnosis didn’t make a difference. Complicated right? Had they reversed it and used the DSM-III criteria for both groups, then there most likely would not have been such a drastic increase.

Let’s use weight as an example to make this a little clearer. Let’s say that in the 1980s children weighing less than 35 pounds at age 4 were considered underweight (regardless of height). Then in the 1990s we changed the criteria and say all 4-year-olds under 45 pounds are considered underweight. Would all the underweight children from the ‘80s be included in this new definition? Yes. Would there also be a significant number of children added to the underweight category by the 1990s definition? Of course. Has the actual number of underweight children increased? Depends on how you look at it. This is broadening of a diagnostic criteria.

Another data set that appears to show drastic rates of increase is the Individuals with Disabilities Education Act (IDEA) data. This is sometimes called the “Child Count” data.

A child diagnosed with autism under IDEA receives additional free education services. For some families this is an absolute godsend. Every year the Federal Government requires reporting of the number of children served by this act. This is where you will see people pulling the numbers like a 1,354% increase. The period of time where this was observed was 1991-2001. But before 1991 autism did not qualify as a reporting category. When you start reporting something new, there is going to be a dramatic increase. Increases will continue to be seen as more people become aware. States have all gradually increased their reporting at different levels and rates. For example, in the school year 2002-03, Oregon reported 4.3 children with autism per 1,000, but Colorado only reported 0.8 children per 1,000.

“Diagnostic Substitution” is another way in which autism rates are often mistakenly seen as elevated. The chart below shows rates of mental retardation decreasing at approximately the same rate that autism increases. Are there fewer children being born with what we used to call mental retardation? Probably not. Behaviors and learning disabilities that were present in order to make these diagnoses remain, we just assign them to a more specific diagnosis which is now under the ASD umbrella. This same pattern has been found in European countries as well.


Prevalence of Autism and Mental RetardationPeople with autism have always been with us. Remember that kid in your class who always wanted to play by himself, barely talked, or just seemed a little distant or different? Prior to the 1990s not many people would have said “Oh, that child has autism.” Now “autism” is a fairly common word in our culture and most people know what it is or someone with an autism diagnosis.

Another very important reason for the increase in the numbers of diagnosis is awareness of the disease by doctors, teachers, and parents. In addition, understanding that the earlier autism is detected the better off the child is in the long run, has pushed pediatricians to be less reluctant in giving a diagnosis of autism. More awareness means more resources and more assistance for families, but it also means parents and health professionals are looking more closely for it. Seek and ye shall find. And well…for many children and families, that’s a good thing.


Thimerosal is a preservative that was used in multi-dose vaccine bottles until 1999 when it was removed for precautionary reasons. Thimerosal is a form of mercury. See our page on vaccine ingredients. It is possible that the way in which the vaccine regulators went about removing thimerosal was alarming for many parents and even for medical professionals. Many people continue to think that thimerosal was in the MMR vaccine but it never was. The MMR vaccine is a “live” vaccine and would not be effective if thimerosal was added. The MMR comes as a powder in a single dose vial that is stored in a freezer and reconstituted with sterile water just prior to being given. Thimerosal was only used in multi-dose vaccine vials, which we no longer use.

If the “mercury in vaccines caused autism” hypothesis was true, then we could expect that the rates of autism would have dropped dramatically when thimerosal was removed from vaccines. Except they didn’t. They keep climbing. That is just one snapshot though. Comparison studies with hundreds of thousands of children who did and did not receive thimerosal in vaccines have been done. Autism occurred at the same rate in each group. (Offit) (Schechter)

The number of vaccines and autism rates

Organic Food GraphAs humans we are constantly looking for cause and effect. People will say the number of vaccines have increased and so has the number of children with autism, so, they must be related. But you could also say the usage of the internet, consumption of organic foods, and cell phones have also increased, so they could be the causes of autism as well. Correlation (2 things that seem related) is not the same as causation. Millions of dollars and hours of research have gone into this question, and the answer is always the same. Vaccines do not cause autism.

The purpose of the chart is not to say organic food causes autism but rather to show how two factors can be seem to be related and yet are certainly not.

Keep in mind that the technology around vaccines has also greatly increased, and we are now protecting our children against more diseases than ever before. A fact that is often not acknowledged in the vaccine debate. Even though we are giving a greater variety of vaccines, we are using less disease particles or antigens and have more combination shots, which reduces the amount of additives in shots. Not that any of these additives have detrimental effect, but we say it to offer reassurance to parents who may be concerned about that.

When parents say, “I’ve done my research,” who are they referring to?

Plenty has been written about Andrew Wakefield, his now debunked research paper from 1998, and the subsequent loss of his medical license. But what about the other voices stating there is a connection between vaccines and autism?

Often people refer to the work of Mark Geier, MD, PhD, a former researcher at the National Institutes of Health, and his son, David Geier. They claim their studies show a strong link between autism and vaccines. But in 2004, when an Institute of Medicine (IOM) panel reviewed all of the evidence on vaccines and autism, they had to exclude the Geier studies, not because they were biased against the Geiers, but because they were “uninterpretable.” The American Association of Pediatrics then released a statement regarding one of the Geier’s studies listing 15 critical errors or omissions.

The Geiers continue to claim they have solid evidence showing a link between autism and vaccines, but their methods are not scientific, their lab is homemade, and their credentials are questionable at best.

We hope that our attempt to convey the facts about autism and vaccines is helpful and reassuring. The search for a cause should continue, but without the distraction of the vaccine argument which takes away precious time and limited resources from the search for a true and proven cause.


Website that lists multiple studies regarding autism.

The Immunization Action Coalition has provided handouts you may find informative.

IAC handout: Evidence Shows Vaccines Unrelated to Autism

IAC handout: Decisions in the Omnibus Autism Proceeding

IAC handout: MMR vaccine does not cause autism. Examine the evidence!

Vaccine Education Center handout: Vaccines and Autism PDF (English)

Vaccine Education Center handout: Las Vacunas Y El Autismo PDF (Español)

CDC’s Vaccine Safety: MMR Vaccine web page

CDC’s Autism Spectrum Disorder (ASD) web section


The full report “Changes in Prevalence of Parent-Reported Autism Spectrum Disorder in School-Aged Children: 2007 to 2011-2012” PDF

Paul T. Shattuck. The Contribution of Diagnostic Substitution to the Growing Administrative Prevalence of Autism in US Special Education. Pediatrics, Vol. 117 No. 4 April 2006, pp. 1028-1037

Taylor B. Vaccines and the changing epidemiology of autism. Child Care Health Dev. 2006 Sep;32(5):511-9.Click here to read

Brown, Ari. Clear Answers and Smart Advice About Your Baby’s Shots, Immunization Action Coalition, 2013,

Gernsbacher M, Three Reasons Not to Believe in an Autism Epidemic PDF

Robert Schechter, MD, MSC; Judith K. Grether, PhD. Continuing Increases in Autism Reported to California’s Developmental Services System, Mercury in Retrograde.  Arch Gen Psychiatry. 2008;65 (1):19-24. 2007.