The vaccine-autism debate is far from over. If anything, it is just getting started.
As the following comments, funding decisions, research priorities and published papers suggest, the U.S. government and many scientists will be researching and discussing this topic for years to come. Here are some reasons why:
I) Federal Health Agencies Endorse More Research
The federal government's four leading health entitites dealing with vaccines and/or autism have all reached consensus: More vaccine safety research is required to fill gaps in knowledge, especially in the context of susceptible subpopulations, mitochondrial impairment, long-tern effects of vaccine-induced fever, seizures and brain injury, and other factors. Millions of dollars will be spent investigating these factors, and not because health officials somehow caved in to parental pressure. Mercury in vaccines, for example, was designated as one of the CDC's "high priority" autism research issues, following an "extensive review of the literature, based on how strongly they seemed to be associated with ASD."
Centers for Disease Control and Prevention Office of Immunization Saftey
The CDC will study autism "as a possible clinical outcome of immunization" as part of its new 5-year research plan. It will also study mitochondrial dysfunction and the risk for "post-vaccine neurological deterioration," and will convene an expert panel on the feasibility of studying health outcomes, including autism, among vaccinated and unvaccinated children.
Centers for Disease Control and Prevention Study to Explore Early Development
NOTE - THIS WEBPAGE WAS RECENTLY ALTERED BY CDC TO REMOVE REFERENCES TO VACCINES, MERCURY AND AUTOIMMUNITY - THE ARCHIVED PAGE IS HERE:
The CDC is currently looking at environmental, genetic and socioeconomic risk factors for ASD, including vaccines and mercury. "We chose to look at vaccines and other types of medical procedures that may have mercury exposure," the CDC says. The agency "designated these factors as high priority" following "an extensive review of the literature, based on how strongly they seemed to be associated with ASD." Selected mercury exposures include "vaccines that the mom received during pregnancy, the child's vaccine exposures after birth and specific other factors such as RhoGAM treatment in pregnancy if the mom has developed an immune response against the fetus that can harm it."
Interagency Autism Coordinating Committee (IACC) -- Includes CDC, HHS, NIH etc.
The nation's leading autism research entity, the IACC, recently announced funding for studies of environmental factors for ASD, such as toxic exposures and "adverse events following immunization (such as fever and seizures), and mitochondrial impairment." It will also fund studies to determine if some subpopulations are "more susceptible to environmental exposures (e.g., immune challenges related to infections, vaccinations, or underlying autoimmune problems)," and will continue to coordinate with the National Vaccine Advisory Committee on "public concerns regarding a possible vaccine/ASD link." The IACC has also concluded that existing population-based vaccine-autism studies are "limited in their ability to detect small susceptible subpopulations."
National Institutes of Health Early Autism Risk Longitudinal Investigation
A network of NIH agencies and affiliated sites are following some 1,200 pregnant women who already have a child with autism to identify the earliest potential causes and "possible environmental risk factors and their interplay with genetic susceptibility during the prenatal, neonatal and early postnatal periods." Researchers are reviewing each child's medical records, including vaccination history. They are also asking about mercury exposures through flu shots during pregnancy, ambient air pollution, seafood consumption, dental amalgams, and thimerosal exposure through contact lens solutions and other OTC products.
U.S. Dept of Health and Human Services National Vaccine Advisory Committee
The nation's leading experts on vaccine safey recently endorsed the study of adverse events following immunization (e.g., fever and seizures) to see if they increase autism risk. The NVAC also supports an expert committee to consider examining outcomes in unvaccinated, vaccine delayed and vaccinated children, including autism. The Committee recommends more study of "the possible occurrence of ASD in a small number of children subsequent to MMR vaccination" especially given "recent research around the incidence of mitochondrial dysfunction in children with an ASD phenotype."
The NVAC also recommends studying adverse vaccine reactions in subsets of ASD children, given "recent developments around mitochondrial dysfunction," and because some children "may be at elevated risk of reduced neurological functioning, possibly including developing ASD, subsequent to vaccination."
U.S. Dept of Health and Human Services Vaccine Injury Compensation Program
The so-called Federal "Vaccine Court" has asked an Institute of Medicine committee to consider adverse events from the DTaP and MMR vaccines, including autism and autism spectrum disorders. The IOM committee will will consider vaccine-associated "secondary" autism or autistic features arising from chronic encephalopathy, mitochondrial disorders and/or other underlying disorders. The vaccine injury program has asked the committee to consider "primary autism" in light of "recent theories of neuro-inflammation and hyper-arousal/over-excitation of the immune system via multiple simultaneous antigenic stimulation" (several vaccines at once).
Scientists Call For More Studies
Today, more scientists and research institutions are supporting further inquiry into the role of environmental toxins in the onset of autism spectrum disorder. While many of them doubt that vaccines are responsible for the dramatic increase in autism incidence, they point to knowledge gaps concerning susceptible subgroups that may have been missed in large population studies of MMR vaccine, thimerosal and ASD.
David Amaral, PhD, Director of Research, University of California, Davis M.I.N.D. Institute. PBS, April 2011:
In general, vaccines are not the culprit, (but) there may be a small subset of children who may be particularly vulnerable to vaccines if the child was ill, if the child had a precondition, like a mitochondrial defect. Vaccinations for those children actually may be the environmental factor that tipped them over the edge of autism.
Duane Alexander, MD, former Director of the National Institute of Child Health and Human Development (NICHD), current Senior Scientific Advisor to NIH's Fogarty International Center. Interview, October 2009:
One question [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. The trigger could be some adverse or cross-reacting response to a vaccine component or a mitochondrial disorder increasing the adverse response to vaccine-associated fever.
Geraldine Dawson, PhD, Chief Science Officer, Autism Speaks. July, 2009:
It remains scientifically plausible that the challenge to the immune system resulting from a vaccine (or other immunological challenges) could, in susceptible individuals, have adverse consequences for the developing brain. Evidence does not support the theory that vaccines are causing an autism epidemic. However, it is plausible that specific genetic or medical factors that are present in a small minority of individuals might lead to an adverse response to a vaccine and trigger the onset of autism symptoms.
Story Landis, PhD, Director of the National Institute of Neurodevelopmental Disorders and Stroke (NINDS), former member, IACC. Statement, October 2009:
It is important for autism researchers to study the children who have been most profoundly affected by their response to vaccines.
Julie Gerberding, MD, former Director of the Centers for Disease Control and Prevention, current President of Merck Vaccines. CNN, March 2008:
If a child was immunized, got a fever, had other complications from the vaccines. And if you're predisposed with the mitochondrial disorder, it can certainly set off some damage. Some of the symptoms can be symptoms that have characteristics of autism... I think we have to have an open mind about this.
Martha Herbert, MD, PhD, Assistant Professor of Neurology at Harvard Medical School, Pediatric Neurologist at Massachusetts General Hospital. PBS, April 2011:
I think it's possible that you could have a genetic subgroup. You also might have an immune subgroup. There are a variety of subgroups. But the problem with the (vaccine-autism) population studies is they don't... they aren't necessarily designed to have the statistical power to find subgroups like that if the subgroups are small.
Autism Speaks, Official Statement. February 2009:
We will continue to support authoritative research that addresses unanswered questions about whether certain subgroups of individuals with particular underlying medical or genetic conditions may be more vulnerable to adverse effects of vaccines. While large scale studies have not shown a link between vaccines and autism, there are lingering legitimate questions about the safety of vaccines that must be addressed.
III) Recent Papers and Future Study
Studies that refute an autism-vaccine association tend to get widespread coverage in the media, but studies suggesting that more research is needed tend to get overlooked. The following are just a few recently published papers, some from foreign journals. They are not presented here as evidence of an association between immunization and autism, but rather to demonstrate the types of investigations that researchers might pursue in the years to come.
Mitochondrial Impairment and Lead Found in Saudi Children with ASD -- Vaccines May Trigger Metabolic Stress and Regression in Mild Impairment Cases
"Plasma fatty acids as diagnostic markers in autistic patients from Saudi Arabia"
Lipids in Health and Disease, 2011 Apr 21;10(1):62.
This small study found that "fatty acids are altered in the plasma of autistic patients," and the differences were related to "oxidative stress, mitochondrial dysfunction and the high lead concentration previously reported in Saudi autistic patients." Taken together with three related Saudi studies, the authors "confirmed the impairment of energy metabolism in Saudi autistic patients, which could be correlated to oxidative stress." Vitamin E and glutathione were "remarkably lower" in ASD patients vs. controls. Saudi ASD children "are under oxidative stress due to GSH (glutathione) depletion," the authors said. "This confirms that oxidative stress and defective mitochondrial energy production could represent the primary causative factor in the pathogenesis of autism." And they added, "There may be an initial period of normal development and function before decompensation in association with metabolic stress or immune activation, such as fasting, illness or vaccination."
Vaccine-Induced Fever Caused ASD Regression in Four Chidren with Mitochondrial Dysfunction
"Fever plus mitochondrial disease could be risk factors for autistic regression"
Journal of Child Neurology, 2010 Apr;25(4):429-34.
Researchers looked at 28 children with ASD and mitochondrial disease and found that 17 of them (60.7 percent) had gone through autistic regression, and 12 of the regressive cases happened following fever. Among the 12 children who regressed after fever, a third of them (4) had fever associated with vaccination, as was the case of Hannah Poling v. HHS.
Birth Dose of Hepatitis-B Vaccine Associated with Increased ASD Risk in Boys
"Hepatitis B vaccination of male neonates and autism diagnosis, NHIS 1997-2002"
Journal of Toxicology and Environmental Health 2010;73(24):1665-77.
This cross-sectional study used weighted probability samples from National Health Interview Survey 1997-2002. It findings "suggest that U.S. male neonates vaccinated with the hepatitis B vaccine prior to 1999 had a threefold higher risk for parental report of autism diagnosis compared to boys not vaccinated as neonates."
Thimerosal may contribute to infant neurodevelopmental disorders, including autism.
"Lasting neuropathological changes in rat brain after intermittent neonatal administration of thimerosal"
Folia Neuropathologica 2010;48(4):258-69.
This study found that "numerous neuropathological changes were observed in young adult rats treated postnatally with thimerosal," and that "These findings document neurotoxic effects of thimerosal, at doses equivalent to those used in infant vaccines or higher, in developing rat brain, suggesting likely involvement of this mercurial in neurodevelopmental disorders." The authors concluded that thimerosal is "possibly contributing to pediatric neurodevelopmental disorders, including autism."
Risk of Neurotoxicity from Thimerosal is Plausible, at Least for Susceptible Infants
"Making sense of epidemiological studies of young children exposed to thimerosal in vaccines"
Clinica Chimica Acta, International Journal of Clinical Chemisty, 2010 Nov 11;411(21-22):1580-6
Although this review did not look autism, it compared eight epidemiological studies conducted in the U.S., UK and Italy on "neurological issues and thimerosal-containing vaccines (TCV)" and found the data were "insufficient to establish non-toxicity for infants and young children." The review identified "ambiguity" in some of the studies, likely caused by confounding variables.
"The risk of neurotoxicity due to low doses of thimerosal is plausible at least for susceptible infants," the author concluded. "There is a need to address these issues in less developed countries still using TCV in pregnant mothers, newborns, and young children. Developing countries should intensify campaigns that include breastfeeding among efforts to help prime the central nervous system to tolerate exposure to neurotoxic substances, especially thimerosal."