Vaccines and autism:
Science, politics, and the media
What is science?

Science is the systematic enterprise of
gathering knowledge about the world and
organizing and condensing that knowledge
into testable laws and theories
Wilson, Edmund O. in Consilience
What is science?
Formulate a hypothesis and establish
burdens of proof. Proofs are subjected to
statistical analysis.

Science includes rigorous controls that
allows one to isolate the effects of one
variable.

Two Foundations of Science
Scientific data should be subjected to peerreview (published in good journals)

Scientific data should be confirmed by
other investigators (data must be
reproducible)

Park, R. Voodoo Science: the road from foolishness to
fraud (Oxford University Press, 2000)
Autism and vaccines
A major cause of the Roman empire’s decline…was its
replacement of stone aqueducts by lead pipes…Roman
engineers, the best in the world, turned their fellow citizens
into neurologic cripples. Today our own “best and brightest”
with the best of intentions, achieve the same end through
childhood vaccination programs yielding the modern
scourges of hyperactivity, learning disabilities, autism,
appetite disorders, and impulsive violence.
Coulter, Harris, PhD, 1982
Wakefield, A.J., et al. Lancet 351: 637-641, 1998.
The “Wakefield” study
Theory: The MMR vaccine induces a series
of events that includes intestinal
inflammation, loss of intestinal barrier
function, entrance into the bloodstream of
encephalopathic proteins, and subsequent
development of autism.

Study design: 12 children (8 with autism) in
the United Kingdom who recently received
the MMR vaccine.

The “Wakefield” study
Findings in support of theory
Symptoms of autism first noted by parents
within 1 month of receiving the MMR
vaccine in all eight children.

Seven of eight children with autism had
non-specific colitis and “reactive ileal and
colonic hyperplasia” associated with GI
symptoms.

The “Wakefield” study
Findings at variance with hypothesis
Cannot assign causal link between receipt
of vaccine and onset of autism given absence
of control group.

Determining causality
Disease
No disease
Vaccine
a
b
No vaccine
c
d
Risk in “vaccine” group =
Risk in “no vaccine” group
a /a + b
c/ c + d
The Power of Box A
“Popular
induction depends upon the
emotional interest of the instances, not on
their number.” (Bertrand Russell, 1927)
Daniel Kahneman and the science of
uncertainty: “Judgment Under Uncertainty:
Heuristics and Biases.”

Rotavirus
ACIP.
vaccine and intussusception at the

Extraordinary claims should be backed up
by extraordinary evidence
Sagan, Carl
Consequence of MMR fears
Between 1989 and 1991, about 70% of
children in US were immunized with measles
vaccine.

As a consequence, 55,000 cases of measles
resulted in 11,000 hospital admissions and
123 deaths.

Recent outbreaks of measles in England
and Ireland.

The “Denmark”
study
Retrospective cohort study of all children
born in Denmark between 1991 and 1998.

Cohort included 537,303 children. 444,655
(82%) children had received the MMR
vaccine.

Madsen KM, et al. A population-based study of measles,
mumps, and rubella vaccination and autism. N Engl J
Med 2002;347:1477-1482.
The “Denmark”
study
RR for vaccinated as compared with
unvaccinated children for development of
autism was 0.92 (95% CI, 0.68-1.24) and for
ASD was 0.83 (95% CI, 0.65-1.07).

No association between the age at the time
of vaccination or the time since vaccination,
and the development of autism.

Science and the media
“We cannot rule out the possibility that, in
certain isolated, rare instances, the vaccine
might have caused a rare case of autism,”
said Dr. Hershel Jick of Boston University
Medical Center. “But it is certainly not the
major villain.”

Los Angeles Times, March, 2001
Science and politics

“You (the IOM) put out a report to the
people of this country saying that it (the
MMR vaccine) doesn’t cause autism and
then you’ve got an out in the back of the
thing. You can’t tell me under oath that there
is no causal link, because you just don’t
know, do you?”
Dan Burton (R-Ind), April 25th, 2001
Science and the media
60 Minutes:
“The MMR Vaccine”
Host: Ed Bradley
Producer: Trevor Nelson
Date Aired: November 12, 2000
Lessons for the media

Understand the basic tenets of science.
Studies that have not been both peerreviewed and reproduced should be
interpreted with caution.
Difference between balance and
perspective.


“First, do no harm.”
Lessons for parents
Understand the basic principles of science.
Reasonable to be skeptical of scientists (or
those representing themselves as scientists),
but not reasonable to be skeptical of the
scientific method.

Vaccine Education Center at
The Children’s Hospital of Philadelphia®
Facts About
Childhood Vaccines
215-590-9990
vaccine.chop.edu