[back] Danish study
on Autism and MMR Vaccine Shows
Need for Biological Research
(Cranford, NJ, November 6) The newly released study on autism and the measles-mumps-rubella vaccine (A Population Based Study of Measles, Mumps and Rubella Vaccination and Autism. New England Journal of Medicine, Vol 347, No 19; Nov 7, 2002: 1477-1483, by Kreesten Meldgaard,et al) is a welcome addition to autism epidemiology. Unfortunately, the study conclusions appear overreaching, claiming that this analysis is the final word on autism and vaccines and implying that more research on the topic is unnecessary. Safe Minds asserts that other vaccines besides MMR may be involved in autism, and that only biological research, not epidemiology, can answer the question of whether the MMR vaccine plays a role in autism.
It is important to note that the study only focused on the MMR vaccine, and not vaccines also implicated in autism which contain the mercury preservative thimerosal, explains Sallie Bernard, executive director of Safe Minds. The study also failed to investigate whether the MMR vaccine might be interacting with the thimerosal from other vaccines to increase the severity of symptoms in children who already have autism. Finally, the study did not differentiate between regressive autism, which is the type being linked to MMR vaccine, and the more prevalent early onset autism, which is the type being linked to thimerosal.
Safe Minds is an advocacy organization which focuses on the role of mercury in neurodevelopmental disrorders, including autism. It was founded by parents of autistic children. Thimerosal contains 50% ethylmercury and has been used in most recommended childhood vaccines, including the Diphtheria-Tetanus-Pertussis (DTP), Haemophilus influenzae type B (HiB), and Hepatitis B (Hep B) vaccines.
Research studies have shown that mercury exposure in utero or during early postnatal life the time when thimerosal vaccines are being given can cause immune system abnormalities which predispose the child to ongoing viral infections. It is biologically plausible that this immune disruption may have allowed the live measles virus component in the MMR vaccine to persist in susceptible autistic children, making the symptoms of the disorder worse. This connection would not be detected through an epidemiology study like the Denmark one. Nor does the Denmark study have the power to detect differences in rates of regressive autism between vaccinated and unvaccinated children, since the number of regressive cases estimated to be 10%-20% of all autism cases - would be too small.
The overreaching conclusion of the study should not obscure other important findings from this extensive and well planned analysis from Denmark, continued Ms. Bernard. The authors report an increased prevalence of autism in that country, and thus it supports other recent studies that are also showing increases. This rise tells us that an environmental agent is at work worldwide that is driving this trend. We believe that thimerosal and environmental mercury which are worldwide pollutants are behind the surge. Also, Denmark has had lower and later exposures to thimerosal in vaccines, and the report shows that their rate of autism is lower than in the US, which is also consistent with a thimerosal connection.
Safe Minds is encouraged that the Centers for Disease Control sponsored such an extensive study on autism, which shows that this terrible disease is finally getting the attention of public health officials. Safe Minds looks forward to increased support for autism research, especially at the biological level.
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