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What Parents
Should Know About Measles-Mumps-Rubella (MMR) Vaccine and Autism
Q. Is there a link between measles vaccination and autism?
- No, there is no scientifically proven link between measles
vaccination and autism.
- Extensive reports from both the American Academy of Pediatrics, the
Institute of Medicine and the Centers for Disease Control and
Prevention conclude that there is no proven association between
Measles-Mumps-Rubella (MMR) vaccine and autism.
- Autism is a chronic developmental disorder, often first identified
in toddlers from age 18 months to 30 months. MMR is administered just
before the peak age of onset of autism. This timing leads some parents
to mistakenly assume a causal relationship. There is no evidence that
MMR causes autism.
- Increasing evidence indicates that autism is determined while the
baby is still in the womb, early in the pregnancy.
Q. What is autism?
- Autism is a spectrum of chronic developmental disorders.
- The main characteristics of autism are difficulties in social
interaction, communication, and restrictive and repetitive interests
and activities.
- Autism may be noted initially in infancy as impaired attachment, but
autism is most often first identified in toddlers, mostly boys, from
18 to 30 months of age.
- Although there is no cure, autism is treatable. Symptoms associated
with autism often improve as children start to acquire language and
learn how to communicate their needs.
Q. What about Dr. Andrew Wakefield’s research claiming a link
between MMR and autism?
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The Journal that published this
flawed study, The Lancet, has recently retracted their position and
have acknowledged error in allowing it to be printed in the first
place. (March, 2004) Also disclosed was the fact that the
study was backed primarily by persons seeking to pursue litigation,
which automatically creates a bias to an already improper study. |
- Dr Wakefield's 1998 paper is simply a description of 12 children who
were referred to his clinic because of diarrhea or abdominal pain. The
12 children also had a history of normal development followed by loss
of certain skills. When a history was taken, questions were asked
about MMR immunizations that had been administered as many as 9 years
earlier and the relationship of these vaccines to onset of loss of
skills. From these data, involving a small sample of children,
Wakefield proposed an association between immunization and autism. Any
association with MMR was based on parental recall about events that
occurred many years earlier, instead of objective data. Further, in
four of the 12 cases, the behavioral disorders predated the bowel
symptoms, which refutes Wakefield’s own theory that bowel
dysfunction (caused by MMR) causes autism. There was clearly selection
bias as the children already had gastrointestinal symptoms. And there
was no control group, a critical omission that casts further doubt on
the findings. This was not a scientific paper but rather a description
of parental recall from a skewed population of children referred to
Wakefield’s clinic.
- Replication of findings is a standard of good science. If research
findings can be reproduced in a separate setting, it affirms those
findings. Dr. Wakefield’s original research showed measles virus in
Crohn's patients. He shared these specimens with his colleagues at
Royal Free Hospital in London, who were then unable to find the
measles virus using even more sensitive methods. Many other scientists
examined intestinal biopsies of Crohn's patients and could not find
measles virus. Wakefield's findings could not be replicated.
- Dr. Wakefield’s 2002 paper in the Journal of Molecular Pathology
is also critically flawed. It claimed that 75 of 91 children with
autism were found to have measles virus genome in intestinal biopsy
tissue as compared with only 5 of 70 control patients. But we know
that after the vaccine is given, the virus is likely to be taken up by
specific immune cells and carried throughout the body (including the
intestine).). To determine if MMR is associated with autism, one must
determine if the finding is specific for children with autism. Put
differently, the control group must match the group of autistic
children for immunization status and for the length of time between
their MMR vaccine and their biopsy. This critical information was
omitted from the paper.
- A study by respected researchers, published this year in the British
Medical Journal, found no rise in incidence of autism in children who
received MMR as compared to those who did not. The authors also showed
that in autistic children, the age at which a child received MMR did
not affect the age at which the diagnosis of autism was made. They
also demonstrated that in the years after the MMR vaccine was
introduced in the United Kingdom, there was no increase in autism
rates in comparison to the years before the vaccine was available.
Q. Why are we seeing a rise in the incidence of autism?
- Physicians use a book called the Diagnostic Statistical Manual to
help them diagnose cases of autism. In the past decade, the guidelines
in that book have changed. They have become more inclusive. So
children who used to be considered "learning delayed" or to
have "behavior problems" may now be more correctly diagnosed
with mild autism.
- Parents and medical professionals are simply more aware of the
condition and are more likely to pursue a diagnosis and treatment than
in years past. As there are more state and federally funded programs
available for children with autism, there is an increased incentive to
make a diagnosis, so those children will have access to those
programs.
- A recent study in the British Medical Journal found no rise in
incidence of autism in children who received MMR as compared to those
who did not. The authors also showed that in autistic children (both
ASD and classical) the age at which a child received MMR did not
affect the age at which the diagnosis of autism was made.
Q. Why not separate the measles, mumps and rubella vaccines and
immunize for each illness individually?
- A panel of experts convened in June, 2000, by the Academy concluded
in its report that "separate administration of measles, mumps and
rubella vaccines to children provides no benefit over administration
of the combination MMR vaccine and would result in delayed or missed
immunizations."
- The separate vaccines are not an option because they are not
currently being manufactured in this country.
- There is no scientific reason for or benefit to separating the
vaccines. By separating them, we are putting children (and pregnant
women who may be exposed to them) at increased risk by extending the
amount of time they go unvaccinated.
Q. What does all this mean to pediatricians and parents?
- This means that pediatricians can and should feel confident using
MMR vaccine and recommending it for their patients, and parents can
feel confident about it as well.
Q. Why should we still vaccinate against measles when cases are so
uncommon?
- Measles virus is common throughout the world and is frequently
imported into the U.S. In 1996, 47 cases were known to have been
imported by people traveling to the U.S. from other countries. In 1998
and 1999 all U.S. measles cases reported were linked to imported
cases.
- Before measles immunizations were available, nearly everyone in the
U.S. got measles. There were approximately 3 to 4 million measles
cases each year. An average of 450 measles-associated deaths were
reported each year between 1953 and 1963.
- If we stop vaccinating, we would see more people die from measles.
During the 1998 - 1999 measles outbreak in the U.S., one out of every
500 people who contracted measles died.
Q. What are the complications of measles vaccination?
- Measles vaccine is safe; most people have no reactions.
- About 5 percent to 15 percent of vaccine recipients may develop a
fever five to 12 days after MMR vaccination. The fever usually lasts
one to two days and usually is not associated with other symptoms.
About 5 percent of MMR recipients may develop a rash one to two weeks
after immunization.
- Central nervous system disturbances, such as encephalitis, have been
reported with a frequency of less than one per 1 million doses of MMR
vaccination administered, a frequency many times lower than the
incidence of serious central nervous system disorders that follow
natural infection at a rate of one per 800.
Q. Aren’t measles, mumps and rubella relatively harmless illnesses?
Measles
- Highly contagious respiratory disease
- Causes rash, high fever, cough, runny nose and red, watery eyes,
lasting about a week
- Causes ear infections and pneumonia in 1 out of every 12 children
who get it
- Causes encephalitis that can lead to convulsions, deafness or mental
retardation in 1 to 2 of every 2,000 people who get it
- In 1989-90, there was a measles epidemic, resulting in 55,000 cases
of measles, 11,000 hospitalizations, and 123 deaths. The majority of
these cases were in unimmunized preschool children
- Of every 1,000 people who get measles, 1 to 2 will die
- Measles vaccine (contained in MMR, MR and measles vaccines) can
prevent this disease
Mumps
- Causes fever, headache and swelling of one or both cheeks or sides
of the jaw
- Four to six persons out of 100 who get mumps will get meningitis
- Inflammation of the testicles occurs in about 4 of every 10 adult
males who get mumps, which may lead to sterility
- May result in hearing loss, which is usually permanent
Rubella
- Also known as German measles
- Mild disease in children and young adults, causing rash and fever
for 2 to 3 days
- Causes devastating birth defects if contracted by a pregnant woman;
there is at least 80% chance of damage to the fetus if a woman is
infected early in pregnancy
Q. What causes autism?
The causes of autism are not known for certain. Most experts agree
that autism is a condition that begins before birth. The current theory
favored by many experts is that autism is a genetically based disorder.
Studies of people with autism have identified abnormalities in brain
structures that develop in the first few weeks of gestation (that is,
while the fetus is in the womb).
Q. What is being done to make sure that vaccines stay safe?
The Centers for Disease Control and Prevention, the National
Institutes of Health and the Food and Drug Administration continue to
conduct studies to further ensure the safety of vaccines.
For more information about immunizations, access the National
Immunization Program from the Centers for Disease Control and
Prevention: http://www.cdc.gov/nip
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