NICHD

National Institute 

of Child Health and 

Human Development 

National Institutes of Health 

Autism 

Research at 

the NICHD 

For more information, 

contact the NICHD at: 

NICHD Clearinghouse 

P.O. Box 3006, Rockville, MD 20847 

1-800-370-2943 

Fax: 301-984-1473 

E-mail: NICHDclearinghouse@mail.nih.gov 

Internet: www.nichd.nih.gov/autism 

Autism and the 

MMR Vaccine 

What is autism? 

Autism is a complex biological disorder of development 

that lasts throughout a person’s life. People with 

autism have problems with social interaction and 

communication, so they may have trouble having a 

conversation with you, or they may not look you in the 

eye. They sometimes have behaviors that they have to 

do or that they do over and over, like not being able to 

listen until their pencils are lined up or saying the same 

sentence again and again. They may flap their arms to 

tell you they are happy, or they might hurt themselves 

to tell you they are not. 

One person with autism may have different symptoms, 

show different behaviors, and come from different 

environments than others with autism. Because of 

these differences, doctors now think of autism as a 

“spectrum” disorder, or a group of disorders with a 

range of similar features. Doctors classify people with 

autism spectrum disorder (ASD) based on their autistic 

symptoms. A person with mild autistic symptoms is at 

one end of the spectrum. A person with more serious 

symptoms of autism is at the other end of the 

spectrum. But they both have a form of ASD. 

The National Institute of Child Health and Human 

Development (NICHD), part of the National Institutes 

of Health (NIH), is one of the NIH Institutes doing 

research into various aspects of autism, including its 

causes, how many people have it, and its treatments. 

www.nichd.nih.gov
AUTISM RESEARCH AT THE NICHD

2
 

Why do people think 

that vaccines can 

cause autism? 

Some parents and families of children with 

autism believe that the Measles/Mumps/ 

Rubella (MMR) vaccine caused their children’s 

autism. These parents report that their 

children were “normal” until they received the 

MMR vaccine. Then, after getting the vaccine, 

their children started showing symptoms of 

autism. Because the symptoms of autism begin 

to occur around the same time as the child’s 

MMR vaccination, parents and families see the 

vaccine as the cause of the autism. However, 

just because the events happen around the 

same time does not mean that one caused the 

other. Although children receive many other 

vaccines in addition to the MMR vaccine, 

these other vaccines have not been identified as 

possible causes of autism. 

These parents’ beliefs and observations were 

reinforced by a small study of bowel disease 

and autism, published by Wakefield and his 

colleagues in 1998 (Wakefield et al 1998). The 

study’s authors suggested that there was a link 

between the MMR vaccine and autism. This 

study did not include scientific testing to find 

out if there was a link. The authors relied on 

the reports of parents and families of the 12 

children with autism involved in the study to 

make their suggestion. The study did not 

provide scientific proof that there was any link. 

Since this study was published in 1998, a 

number of other studies have also been 

published that suggested a link between the 

MMR vaccine and autism (Singh et al 1998; 

Horvath et al 1999; O’Leary et al 2000; 

Wakefield et al 2000; Kawashima et al 2000), 

but none of these provide scientific proof of 

such a link. 

To date there is no definite, scientific proof 

that any vaccine or combination of vaccines 

can cause autism. It’s important to know that 

vaccines actually help the immune system to 

defend the body. 

How do vaccines help the immune 

system defend the body? 

The immune system has cells, sometimes called 

memory cells, that remember diseases. If these 

cells meet a disease, they keep track of what it 

looks like so they can recognize it later. When 

the memory cells meet up with the disease 

again, they recognize it and know they need to 

get rid of it. They call in the other parts of the 

immune system to get rid of the disease. In 

some cases, memory cells can recognize a 

disease without ever having to meet up with it, 

which is called “natural” immunity. In other 

cases, the cells need some help to become 

familiar with a disease. 

That help comes in the form of a vaccine. The 

vaccine takes a form of the disease that doesn’t 

make you sick and introduces it to the memory 

cells so they know what to look for later. If the 

memory cells ever bump into the disease again, 

they know to call in other cells in the immune 

system to protect the body and get rid of the 

disease. The memory cells of a child keep track 

of diseases well into adulthood, preventing 

such diseases by getting rid of them quickly. In 

this way, vaccines help the immune system by 

making it easier to remember diseases. 
Why do many doctors and 

scientists believe that the 

MMR vaccine does not 

cause autism? 

In 2000, the Institute of Medicine (IOM) at 

the National Academy of Sciences, at the 

request of the Centers for Disease Control and 

Prevention (CDC) and the NIH, conducted a 

review of all the evidence related to the MMR 

vaccine and autism. This independent panel 

examined completed studies, on-going studies, 

published medical and scientific papers, and 

expert testimony to assess whether or not 

there was a link between autism and the 

MMR vaccine. The IOM concluded that 

the evidence reviewed did not support an 

association between autism and the MMR 

vaccine. This and other conclusions 

from the IOM review were released in 

April 2001 (Immunization Safety Review 

Committee 2001). 

Also in 2000, the American Academy of 

Pediatrics (AAP), a professional organization 

for pediatricians with over 55,000 members, 

held a conference on the MMR vaccine and 

autism. Parents, scientists, and practitioners 

presented information on this topic to a 

multidisciplinary panel of experts. Based on 

its review, the AAP also found that the 

available evidence did not support the theory 

that the MMR vaccine caused autism or 

related disorders. The AAP policy statement 

appeared in the May issue of Pediatrics (Halsey 

et al 2001). 

In 1999, Taylor and colleagues published a 

study (Taylor et al 1999) that argued against 

AUTISM AND THE MMR VACCINE 

the suggested link between autism and the 

MMR vaccine suggested in the Wakefield 

study. Taylor’s study looked at all the known 

cases of ASD in children living in certain 

districts of London who were born in 1979, 

or later. Researchers then matched the ASD 

patients with an independent registry of 

vaccinations. The results of this study 

showed that: 

●	 The number of ASD cases had increased 

steadily since 1979, but there was no sharp 

increase in the number of cases after doctors 

started using the MMR vaccine in 1988. 

●	 Children showed symptoms of ASD and 

were diagnosed with ASD at the same ages, 

regardless of whether they were vaccinated 

before or after 18 months of age. This 

finding is important because if the MMR 

vaccine caused ASD, the children who 

were vaccinated earlier would show 

symptoms earlier. 

●	 By age two, vaccination coverage (the 

number of children who received vaccines) 

among children with ASD was nearly the 

same as vaccination coverage for children the 

same age who did not have ASD throughout 

the region. If the MMR vaccine and ASD 

autism were linked, then a greater number 

of children who had been vaccinated 

throughout the region would have ASD. 

●	 The first signs of autistic behavior or first 

diagnosis of ASD was not more likely to 

occur in time periods following the MMR 

vaccine than in other time periods. 

3
AUTISM RESEARCH AT THE NICHD

4
 

Also in 1999, the United Kingdom’s 

Committee on Safety of Medicine examined 

hundreds of reports collected by lawyers of 

patients with autism and similar disorders that 

families said they developed after receiving the 

MMR or MR vaccine. After a systematic, 

standardized review of the case information, 

the Committee found that the information did 

not support any link between vaccines and 

autism. Based on the evidence, the Committee 

concluded that there was no cause for concern 

about the safety of MMR or MR vaccines 

(Medicines Commission Agency 1999). 

A study, done in Sweden in 1998, also showed 

no evidence of association between the MMR 

vaccine and autism. The study compared the 

number of autism cases in children from two 

Swedish towns before 1982, when local doctors 

first started using the MMR vaccine, and after 

1982. The results showed no difference in 

the rate of autism between the two groups 

of children in either town (Gillberg & 

Heijbel 1998). 

Another study, done in England in 1997, 

looked at any possible link between the 

measles-specific vaccine (one part of the MMR 

vaccine) and different problems that result 

from damage to the nervous system, such as 

learning disabilities and behavior problems. 

These researchers found no proof that the 

measles vaccine was in any way linked to 

long-term damage to the nervous system 

(Miller et al 1997). 

Is there any research going 

on to find out if the MMR 

vaccine is linked to autism? 

The NIH is doing a number of things to 

look into the claims about MMR vaccines 

and autism: 

●	 The Network on the Neurobiology and 

Genetics of Autism: Collaborative Programs 

of Excellence in Autism (CPEA), funded by 

the NICHD and the National Institute on 

Deafness and Other Communication 

Disorders (NIDCD), with additional 

funding from the CDC, are working 

together to study autism and the MMR 

vaccine. This research will examine people 

diagnosed with autism who seemed to 

develop normally, but then started to show 

autistic symptoms. This type of situation is 

called “regression.” To learn as much as 

possible about these patients, researchers will 

compare them to people who do not have 

autism, and to people who showed autistic 

symptoms since birth, called classic autism. 

CPEA researchers will compare vaccination 

records to see if the onset of autism was 

associated with receipt of MMR and other 

vaccines. Lab tests will then look for any 

evidence of persistent infections that could 

be related to the MMR vaccine. 
●	 The NICHD is also working with other 

NIH Institutes, the CDC, the 

Environmental Protection Agency (EPA), 

and other federal agencies to conduct a large, 

long-term study of the effects of the 

environment on children’s health. This study 

will follow 100,000 children from before 

birth to age 20, to track their growth and 

development, as well as their genetic 

blueprints and environmental factors that 

they encounter. Researchers hope to develop 

theories about whether environmental events, 

like environmental pollutants or vaccines, 

can cause abnormal development, such as 

autism, asthma, or other childhood disorders 

that have shown dramatic increase. The 

study is currently under design. 

●	 Another NIH Institute, the National 

Institute of Neurological Disorders and 

Stroke (NINDS) is also conducting a 

retrospective case-control study to identify 

any molecular markers in neonatal blood of 

children with autism, with support from the 

California Department of Health Services 

and the Division of Bioengineering and 

Physical Science (DBEPS) at the NIH. 

●	 In 1998, the NIH, led by the NICHD and 

the NINDS, sponsored a conference on 

ASDs. These and other NIH Institutes 

formed an expert panel, which also included 

15 professional organizations and three 

parents’ groups, and began a review of over 

AUTISM AND THE MMR VACCINE 

2,500 scientific articles to develop a system 

for diagnosing ASDs. The panel published 

its findings in the Journal of Autism and 

Developmental Disorders in 1999 (Filipek et al 

1999). In 2000, the panel’s report was 

adopted as a practice parameter by the 

American Academy of Neurology and the 

Child Neurology Society (Filipek et al 2000). 

Practice parameter: screening and diagnosis of 

autism gives doctors and other health 

professionals the first, standardized method 

for diagnosing autism and ASDs based on 

scientific evidence. 

In addition, the NIH is in the process of 

implementing the autism aspects of the 

Children’s Health Act of 2000. This Act, 

which was signed into law in October 2000, 

charges the NIH with the, “Expansion, 

intensification, and coordination of activities of 

the NIH with respect to research on autism.” 

All of the NIH Institutes that fund autism 

research are working together to establish 

“Centers of Excellence” to focus on autism 

research. In addition, the NIH will form a 

committee with representatives from parents’ 

groups and other federal agencies to coordinate 

autism research activities throughout the 

federal government and to enhance efforts to 

educate doctors and other health care 

professionals, and parents, and other child 

caretakers, about autism. 

5
AUTISM RESEARCH AT THE NICHD

6
 

Aren’t the diseases 

prevented by the MMR 

vaccine mild, when 

compared to the life-long 

symptoms of autism? 

The diseases that the MMR vaccine prevents, 

measles, mumps, and rubella (also called 

German measles), are actually very serious. 

Many times, the symptoms and effects of these 

diseases are just as serious and life-long as the 

symptoms of autism. In some cases, these 

diseases result in death. If people stop getting 

vaccines, the number of cases of these diseases 

will increase, and with it, the number of deaths 

and serious health problems. 

Measles is a life-threatening disease that spreads 

quickly and easily. Before the vaccine was 

available in the U.S., nearly everyone who was 

exposed to measles got the measles, with nearly 

three-to-four million cases each year. The 

symptoms of measles include a rash, high fever, 

cough, runny nose, and watery eyes. But, if 

not treated, these seemingly mild symptoms 

can lead to conditions such as pneumonia, 

seizures, and water and swelling around the 

brain. For one-in-500 to one-in-1,000 people, 

measles causes death. High levels of 

immunization in the U.S. have led to a 

99 percent decrease in measles cases since 

doctors first started using the vaccine. But in 

poorer countries of the world, where vaccines 

aren’t as common, nearly 900,000 people died 

from causes related to measles in 1998. 

Mumps, which the MMR vaccine also protects 

against, was a major cause of deafness in 

children before doctors started using vaccines 

to prevent it. Even though it tends to be mild 

in children, mumps is dangerous for adults, 

with side effects that can include paralysis, 

seizures, and fluid in the brain. Before the 

vaccine for mumps was available, there were 

about 212,000 cases of mumps each year in the 

U.S. In 1998, there were only 606 cases of 

mumps in the U.S. 

The last disease prevented by the MMR 

vaccine, rubella, is harmful to pregnant women 

and their growing babies. If a pregnant woman 

gets rubella, her baby may develop a life-long 

condition that includes heart defects, mental 

retardation, and deafness. In some cases, the 

baby’s condition is so severe that the baby dies. 

In 1964-65, before the vaccine for rubella was 

available, 20,000 babies were born to mothers 

who had rubella. Of those 20,000 born, 

11,600 were deaf, 3,580 were blind, and 1,800 

were mentally retarded. 

Note: Disease statistics cited in this document came 

from the National Institute of Allergy and Infectious 

Diseases at the NIH and the National Immunization 

Program at the CDC. 
Should my child have the 

MMR vaccine? 

Both the CDC and the AAP recommend that 

children receive two doses of the MMR 

vaccine, as long as they have no known health 

problems that prevent the vaccine from being 

effective. The CDC and AAP immunization 

schedules recommend that the first dose be 

given at age 12-to-15 months, while the second 

dose should be given at either four-to-six years 

of age or 11-to-12 years of age. 

Allergies, immune system diseases like HIV, or 

other sicknesses can interact with a vaccine to 

make it less effective. These interactions can 

sometimes cause other health problems. If 

your child is sick, your doctor may delay the 

vaccination until your child is healthy. For 

example, a child with a fever should not have a 

vaccination until the fever is gone. Make sure 

you give a complete description of your child’s 

current health and health history to your 

child’s doctor at every visit, so he or she can 

help you make an informed choice about the 

timing of your child’s vaccinations. 

References

Filipek PA, Accardo PJ, Ashwal S, Baranek GT, Cook, Jr 

EH, Dawson G, Gordon B, Gravel JS, Johnson CP, 

Kallen RJ, Levy SE, Minshew NJ, Ozonoff S, Prizant 

BM, Rapin I, Rogers SJ, Stone WL, Teplin SW, 

Tuchman RF, and Volkmar FR. (1999). The screening 

and diagnosis of autism spectrum disorders. Journal of 

Autism and Developmental Disabilities, 29(6):439-484. 

AUTISM AND THE MMR VACCINE 

Filipek PA, Accardo PJ, Ashwal S, Baranek GT, Cook, Jr
 

EH, Dawson G, Gordon B, Gravel JS, Johnson CP,
 

Kallen RJ, Levy SE, Minshew NJ, Ozonoff S, Prizant
 

BM, Rapin I, Rogers SJ, Stone WL, Teplin SW,
 

Tuchman RF, and Volkmar FR. (2000). Practice
 

parameter: screening and diagnosis of autism; Report of
 

the Quality Standards Subcommittee of the American
 

Academy of Neurology and the Child Neurology Society.
 

Neurology, 


55:468-479.
 

Gillberg C and Heijbel H. (1998). MMR and autism.
 

Autism, 2:423-4.
 

Halsey N, Hyman S, and The Conference Writing Panel.
 

(2001). Measles-mumps-rubella vaccine and autistic
 

spectrum disorders. Pediatrics, 107(5): e84-107 


Horvath K, Papadimitriou JC, Rabsztyn A, Drachenberg
 

C, and Tildon JT. (1999). Gatrointestinal abnormalities
 

in children with autistic disorders. J Pediatr, 135(5):559­

563. 

Immunization Safety Review Committee, Board on 

Health Promotion and Disease Prevention, Institute of 

Medicine. (2001). Immunization safety review: measlesmumps-rubella vaccine and autism. Stratton K, Gable A, 

Shetty P, and McCormick M (Eds.). Washington, DC: 

National Academy Press. 

Kawashima H, Mori T, Kashiwaga Y, Takekuma H, 

Hoshika A, and Wakefield A. (2000). Detection and 

sequencing of measles virus from peripheral 

mononuclear cells from patients with inflammatory 

bowel disease and autism. Dig Dis Sci, 45(4):723-729. 

Medicines Commission Agency/Committee on Safety of 

Medicines. (1999). The safety of the MMR vaccine. 

Curr Probl Curr Pharmacovigilance, 25:9-10. 

7
NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT 

Miller D, Wadsworth J, Diamond J, and Ross E. (1997) Wakefield AJ, Murch S, Anthony A, et al. (1998). Ileal 

Measles vaccination and neurological events. Lancet, lymphoid nodular hyperplasia, non-specific colitis, and 

349:730-731. regressive developmental disorders in children. Lancet, 

351:637-641. 

O’Leary JJ, Uhlmann V, and Wakefiled AJ. (2000). 

Measles virus and autism. Lancet, 356:772.	 Wakefield AJ, Anthony A, Murch SH, Thompson M, 

Montgomery SM, Davies S, O’Leary JJ, Phil D, 

Berelowitz M, and Walker-Smith JA. (2000). Singh VK, Lin SX, and Yang VC. (1998). Serological Enterocolitis in children with developmental disorders. association of measles virus and human herpes virus-6 

with brain autoantibodies in autism. Clin Immunol
 Am J Gastroenterol, 95:2285-2295.

Immunopathol, 89:105-108.
 

Taylor B, Miller E, Farrington CP et al. (1999). Autism
 

and measles, mumps, rubella vaccine: no epidemiological
 

evidence of for a causal association. Lancet, 353:2026­

2029.
 

For more information on autism and autism research, including studies 

involving vaccines and autism, contact the NICHD Clearinghouse, at: 

Mail: PO Box 3006, Rockville, MD 20847 

Phone: 1-800-370-2943 

Fax: 301-984-1473 

Email: NICHDClearinghouse@mail.nih.gov 

Internet: www.nichd.nih.gov/autism 

You can also comment on this or other Autism Research at the NICHD 

fact sheets through the Web site. 

For more information on vaccines and vaccine safety, contact the National 

Immunization Program (NIP) at the CDC, at 1-800-232-2522 (English) or 

1-800-232-0233 (Spanish), or visit the NIP web site at www.cdc.gov/nip. 

NIH Pub. No. 01-4963 

June 2001 

8