Letter from Professor Walter 0. Spitzer

Sunday Times May 27 2001

Editor: In the course of travel in Europe, I read a surprising headline in USA Today, "Vaccine is off the hook as the cause of autism. But panel won't dismiss possibility."(See 1. below)

The two parts of the headline are contradictory. I had just finished reading the 74-page Report of the Institute of Medicine's Immunization Safety Review Committee (the panel) released on 4-23-01. There was nothing in the Report or its executive summary to justify such a headline in a reliable national newspaper. I can only link the headline's …"off the hook as the cause of autism" to a public statement of Dr. Marie McCormick, the chairperson of the Committee. In the Institute of Medicine (IOM) press conference she stated: "it [MMR] is as safe as a vaccine can get "(See 2. below)

As an individual evaluator, my view is that the IOM Report itself is 70% to 90% correct in its descriptions of the evidence and in its judgments. The Report concludes: "…evidence favors rejection of a causal relationship at the population level between MMR vaccine and autistic spectrum disorders…"(See 3. below) The foregoing is all based on lacking evidence. The Committee concedes that it could not "…exclude the possibility that MMR vaccine could contribute to ASD in a small number of children…."(See 3. below)

What is a small number of children? If the number were 5% of diagnosed autistics in any large developed country, that would be thousands of persons. The Report recommends: "Conduct further clinical and epidemiological studies of sufficient rigor to identify risk factors and biological markers of ASD…"(See 4. below)

I do not disagree with the Committee's opinions as cited except in degree. Expressed in simpler but consistent language, the IOM Report reads as follows: We do not know whether there is any link between MMR and any autistic disorder. The evidence is inconclusive. More study is needed. I agree with the three conclusions. But for McCormick to say in the releasing press conference, " it is as safe as a vaccine can get" imputes the Chair's personal opinion to the Committee as a whole. It is understandable that the lay press picked the wrong message from the wrong source.

As an epidemiologist who has been a Member of the IOM since 1986, I have been proud of IOM reports in my field that I have examined or co-authored. I am embarrassed by the process of this latest Report and would urge President Shine of the IOM to retract the Report until the message has been clarified. What was released, the IOM Report or the McCormick Position?

I am a worried agnostic on the matter of MMR linked with autism just for reasons given by the IOM Committee. "… because …the proposed biological models linking MMR vaccine to ASD, although far from established, are nevertheless not disproven."3 I believe that immunization is the strongest pillar of public health and prevention. I have no family members with ASD. I would be delighted if effective MMR were also demonstrated to be safe in scientifically admissible safety studies. But let that be the result of the kind of rigorous science that has been called for by the IOM, not unsubstantiated exoneration of MMR by one person.

Walter O. Spitzer, M.D.
Emeritus Professor of Epidemiology
McGill University, Montreal, Canada

1. USA Today, April 24, 2001, p.1
2. Transcript of the IOM press conference at which its Report was released, 4-23-01 - closing remarks.
3. Stratton K et al editors, Immunization Safety Review Committee, Institute of Medicine, Measles-Mumps-Rubella and Autism [prepublication copy], National Academy Press, Washington, DC, 2001, p.36
4. Ibid p. 46