Vaccines and autism:

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• Vaccines and autism
• Science, politics, and the media

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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

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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.

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Two Foundations of Science

• Scientific data should be subjected to
  peer-review (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)

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Autism and vaccines

• A major cause of the Roman empires declinewas
  its replacement of stone aqueducts by lead
  pipesRoman 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

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Wakefield, A.J., et al. Lancet 351 637-641,
1998.
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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.

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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.

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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.

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Determining causality

• Disease No disease
• Vaccine a b
• No vaccine c d
• Risk in vaccine group a /a b
• Risk in no vaccine group c/ c d

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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 vaccine and intussusception at the
  ACIP.

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• Extraordinary claims should be backed up by
  extraordinary evidence
• Sagan, Carl

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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.

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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 20023471477-1482.

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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.

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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

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Science and politics

• You (the IOM) put out a report to the people of
  this country saying that it (the MMR vaccine)
  doesnt cause autism and then youve got an out
  in the back of the thing. You cant tell me under
  oath that there is no causal link, because you
  just dont know, do you?
• Dan Burton (R-Ind), April 25th, 2001

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Science and the media

• 60 Minutes
• The MMR Vaccine
• Host Ed Bradley
• Producer Trevor Nelson
• Date Aired November 12, 2000

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Lessons for the media

• Understand the basic tenets of science. Studies
  that have not been both peer-reviewed and
  reproduced should be interpreted with caution.
• Difference between balance and perspective.
• First, do no harm.

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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.

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Vaccine Education Center at The Childrens
Hospital of Philadelphia
Facts About Childhood Vaccines
215-590-9990 vaccine.chop.edu