Although many recent media reports on the Wakefield scandal left the impression that questions of vaccine safety and specifically, questions of a link between autism and vaccines, have been put to rest for all eternity, such is not the case. Below are excerpts from an interview with the Director of the National Institute of Child Health and Human Development (one of the National Institutes of Health) explaining why they continue to fund such research, as well as research on the safety of vaccines in general.
http://www.autismspeaks.org/science/science_news/nichd_alexander_interview.phpDr. Dawson: What is the mission of NICHD with respect to understanding the etiology of developmental disorders, including ASD? Does this include the role of environmental factors?
Dr. Alexander: . . . . Study of environmental factors as causes or ameliorations of developmental disorders is a major component of our research program. Part of this research goes beyond environmental factors acting alone to look at gene-environment factor interactions. In some cases virtually everyone has a genetic make-up that renders them susceptible to adverse consequences of a given environmental exposure, with only a few protected. In other instances a given environmental exposure may have an adverse effect only on a relatively few people who have a variant genetic constitution that leaves them susceptible to adverse consequences from an environmental exposure; these are difficult to detect, especially if only a few people have this genetic variant that makes them susceptible. In this instance, large numbers of individuals need to be studied to find enough people with the rare variant. This situation is where the National Children's Study (NCS) has a potentially valuable role to play. Of the 100,000 children being recruited, we expect 600 to 700 will be diagnosed with ASD by 3 years of age. We will be able to study the genetic constitution of the children with autism in relation to many environmental exposures (illness, home chemicals, medications, vaccines, and many others) and compare them to a control group in the sample without ASD on this whole range of exposures. If there are genetic variations linked to autism related to any of these exposures, this study should identify them if they are not too rare.
Dr. Dawson: What are examples of legitimate scientific questions that remain to be considered with respect to the role of vaccines as a cause or risk factor for ASD? Why is it important to address those questions?
Dr. Alexander: One question that still remains to be addressed in a study of adequate size and precision is the one described in the preceding response, which is whether there is a subgroup in the population that, on a genetic basis, is more susceptible to some vaccine characteristic or component than most of the population, and may develop an ASD in response to something about vaccination. We know that genetic variations exist that cause adverse reactions to specific foods, medications, or anesthetic agents. It is legitimate to ask whether a similar situation may exist for vaccines. No clear evidence yet exists to implicate a specific relationship, but questions persist about whether there may be subpopulations unable to remove mercury from the body as fast as others, some adverse or cross-reacting response to a vaccine component, a mitochondrial disorder increasing the adverse response to vaccine-associated fever, or other as-yet-unknown responses.
The history of vaccine use holds numerous examples of risk reductions made when research demonstrated vaccine-associated adverse events, even if they were uncommon or only hypothetical. These include stopping smallpox vaccination not long after the disease was eliminated, switching from live polio vaccine to the killed vaccine, shifting to purified antigen rather than whole organism pertussis vaccine, and many others, including removal of Thimerosal as a preservative from children's vaccines. All these changes came from continued research and the desire to maximize public safety even when the adverse events were rare (polio) or hypothetical (Thimerosal). There are still legitimate questions to ask about possible vaccine-associated events, and such questions need to be pursued in the interest of both public safety and maintaining public trust.
Dr. Dawson: What sort of findings from vaccine-related studies might be useful in terms of advancing prevention, diagnosis and treatment for ASD?
Dr. Alexander: Both vaccine- and environment-related studies hold out the possibility of breaking down the group of ASDs into different subgroups based on cause or response to different treatment approaches. Diagnosis can be used not just for autism overall but for the subtype within the spectrum. Knowing causes can permit research to develop different prevention/intervention/ treatment approaches that could personalize care and markedly improve outcomes.
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Bottom line: "We know that genetic variations exist that cause adverse reactions to specific foods, medications, or anesthetic agents. It is legitimate to ask whether a similar situation may exist for vaccines."