AS A PEDIATRICIAN, vaccine researcher and the father of an autistic child, I have great concerns regarding the debate about the safety of our infant and childhood vaccines. The unfounded association that has been proposed by some between vaccines and autism is at best misleading and at worst a serious undermining of children's health.
The vaccine/autism question stems from two separate theories that are unscientific and have been determined to be invalid by the qualified experts in vaccine science. The first claims autism is the result of the combination measles, mumps, rubella (MMR) vaccine. The second claims thimerosal is the autism culprit. Thimerosal is a mercury-based compound that was used in many vaccines since the 1930s, but MMR vaccine does not, and has never, contained thimerosal.
Let's begin with the MMR question. Numerous large-scale studies have shown no increase in autism for children who received the MMR vaccine. The most recent study, published in The New England Journal of Medicine and funded by the National Alliance for Autism Research, examined more than 500,000 Danish children. The study found there was no greater incidence of autism among children who received the MMR vaccine than those who did not.
Scientific organizations including the Centers for Disease Control, the Institute of Medicine and the American Academy of Pediatrics have all said that the scientific evidence does not support a causal link between MMR and autism. Ironically, the only known cause of autism is rubella, which the MMR vaccine prevents.
The second vaccine/autism theory is based on the idea that autism is the result of mercury poisoning from the thimerosal in vaccines. In 1999, public health officials decided that thimerosal should be removed from vaccines as a precautionary measure.
A study on thimerosal conducted by the University of Rochester was published last fall in the British medical journal The Lancet. The study showed that ethyl mercury - which is what thimerosal becomes as it is metabolized - is excreted from the body within seven days and does not appear to build up from one vaccination to the next. Even when it is still in the body following immunization, the levels of this mercury do not exceed the government standard, which is based on a more potentially harmful form of mercury known as methyl mercury - the type found in some types of fish. When the report was released, researchers wrote that children would likely be exposed to more mercury by eating a tuna fish sandwich than by vaccines.
More research into thimerosal is under way, though if thimerosal were the cause of what some believe is a dramatic increase in the incidence of autism, one would expect the incidence to drop dramatically since the removal of thimerosal from vaccines in 1999. But it hasn't. As the father of a child with autism, I know the need for parents to understand the root of this heartbreaking disorder and find something to blame. However, as a medical doctor, I believe a more constructive focus is on advancing treatment options, extending reimbursement policies and finding a cure.
By focusing on unproved theories, we not only risk wasting our precious resources and not finding the real cause of autism, but we also risk parents losing confidence in vaccines, resulting in fewer children being immunized. This would leave our youngest vulnerable to diseases that we have only read about in history books, reversing one of the world's most successful public health programs.
A proposed link between autism and vaccines is a distraction that focuses attention away from the real needs of parents of autistic children, namely finding respite care, searching for a child psychiatrist who accepts health insurance, and getting quality special education through public school systems. Ireland and parts of the United Kingdom are a case study of what happens when the fear spreads through the media; fears of the "MMR jab" have led to a significant drop in the immunization rate, resulting in a dramatic increase in the number of measles and mumps cases. We often forget that measles is still the single leading killer of children in the world. With today's ease of travel, these diseases can quickly be imported into the United States, putting children who are unprotected at great risk of contracting the disease.
Every parent has to decide: Is it worth protecting my child from a real, deadly threat or protecting him from a hypothetical, scientifically unproven leap of logic? I chose the former, and I am confident I made the right decision.
PETER HOTEZ is chairman of the Department of Microbiology and Tropical Medicine at George Washington University. He also is a senior fellow and chairman of the Sabin Vaccine Institute's Scientific Advisory Council. KNIGHT RIDDER/TRIBUNE
CBER Research Projects (This is the FDA) Looks like they are doing a study on this subject. The date is APR 2002
Project Title Vaccine Safety: Pathogenesis of Virus Vaccine Neurotoxicity
Principal Investigator K. M. Carbone
Laboratory Laboratory of Pediatric and Respiratory Viral Diseases; Division of Viral Products; Office of Vaccines Research and Review
Project Summary Since the developing nervous system is uniquely sensitive to damage following virus infection, postnatal CNS development during the first several years of life provides for continued susceptibility of the infant CNS to damage by viral infection after birth. Administering insufficiently attenuated vaccines to infants may place the child's CNS at increased risk for injury. Thus, it is imperative to develop methods of pre-clinical neurovirulence testing with which to predict which vaccines might have significant neurovirulence potential for human CNS.
Thus, it is important to develop valid molecular biological, in vitro and in vivo models to evaluate the pathogenesis of the neurotoxic effects of vaccine viruses. Development of these models will lead to improved safety of childhood vaccines, cost saving and improved predictability of neurovirulence testing, and information obtained in these studies will be useful in testing potentially neurovirulent vaccines (e.g., measles, mumps, HIV, parainfluenza, Japanese encephalitis).
Progress: 2001 CBER Outstanding Regulatory Research Project
- Molecular Markers of Neurotoxicity: We have identified vaccine virus-related perturbations in CNS gene expression by standard semiquantitative RT-PCR and by differential display techniques, including endogenous immune mediators of the CNS. We have recovered un-characterized gene products from new genes that are altered by virus infection of the brain. We have initiated RPA to compare changes in endogenous immune mediators in the CNS in animals infected with low and high neurovirulence strains of mumps virus.
- Animal Models of CNS Diseases Following Childhood Virus Infection: Autism. Viruses are known etiologic agents of autism (e.g., rubella). Therefore, concerns are raised regarding a possible relationship between childhood vaccines and autism. Because no valid animal models existed to study the pathogenesis of the neuroanatomical and behavioral signs of autism, we developed a rat model of autism using neonatal infection with neurotropic viruses. We have characterized autistic-like changes in neuroanatomy, neurochemistry, neurological disease and behavior in these rats. In addition, we have identified regional and developmental changes in neurotransmitters, including serotonin and norepinephrine. A developmental study of damage to developing brain (e.g., cerebellum) in virus infected rats was performed demonstrating anatomical, behavioral and neurological consequences.
Comparison of the neurovirulence of a vaccine and a wild-type mumps virus strain in the developing rat brain.
Rubin SA, Pletnikov M, Carbone KM
J Vet Diagn Invest 1998 Oct;10(4):338-43
Clinical, serologic, and histopathologic characterization of experimental Borna disease in ponies.
Katz JB, Alstad D, Jenny AL, Carbone KM, Rubin SA, Waltrip RW 2nd
Behav Brain Res 1999 Apr;100(1-2):43-50
Developmental brain injury associated with abnormal play behavior in neonatally Borna disease virus-infected Lewis rats: a model of autism.
Pletnikov MV, Rubin SA, Vasudevan K, Moran TH, Carbone KM
Brain Res Bull 1999 Jan 1;48(1):23-30
Borna disease virus-induced hippocampal dentate gyrus damage is associated with spatial learning and memory deficits.
Rubin SA, Sylves P, Vogel M, Pletnikov M, Moran TH, Schwartz GJ, Carbone KM
J Infect Dis 1999 Aug;180(2):521-525
The Mumps Virus Neurovirulence Safety Test in Rhesus Monkeys:A Comparison of Mumps Virus Strains.
Rubin SA, Snoy PJ, Wright KE, Brown EG, Reeve P, Beeler JA, Carbone KM
Physiol Behav 1999 Jul;66(5):823-31
Persistent neonatal Borna disease virus (BDV) infection of the brain causes chronic emotional abnormalities in adult rats.
Pletnikov MV, Rubin SA, Schwartz GJ, Moran TH, Sobotka TJ, Carbone KM
J Virol 2000 Jun 1;74(11):5382-5384
Evaluation of a Neonatal Rat Model for Prediction of Mumps Virus Neurovirulence in Humans.
Rubin SA, Pletnikov M, Taffs R, Snoy PJ, Kobasa D, Brown EG, Wright KE, Carbone KM
Dev Brain Res 2000 Feb 7;119(2):179-85
Effects of neonatal rat Borna disease virus (BDV) infection on the postnatal development of the brain monoaminergic systems.
Pletnikov MV, Rubin SA, Schwartz GJ, Carbone KM, Moran TH
Ann N Y Acad Sci 2001 Jun;939:318-9
Rat model of autism spectrum disorders. Genetic background effects on Borna disease virus-induced developmental brain damage.
Pletnikov MV, Jones ML, Rubin SA, Moran TH, Carbone KM
Clin Microbiol Rev 2001 Jul;14(3):513-27
Borna disease virus and human disease.
Mol Psychiatr 2000 Nov;5(6):577
Borna again, starting from the beginning.
Carbone KM, Pletnikov M
Ann Clin Biochem 2001 Jul;38(Pt 4):348-55
Synthetic peptide-based electrochemiluminescence immunoassay for anti-Borna disease virus p40 and p24 antibodies in rat and horse serum.
Yamaguchi K, Sawada T, Yamane S, Haga S, Ikeda K, Igata-Yi R, Yoshiki K, Matsuoka M, Okabe H, Horii Y, Nawa Y, Waltrip RW 2nd, Carbone KM
Brain Res Dev Brain Res 2001 Jan 31;126(1):1-12
Neonatal Borna disease virus infection (BDV)-induced damage to the cerebellum is associated with sensorimotor deficits in developing Lewis rats.
Pletnikov MV, Rubin SA, Carbone KM, Moran TH, Schwartz GJ
Curr Opin Microbiol 2001 Aug;4(4):467-75
Borna disease: virus-induced neurobehavioral disease pathogenesis.
Carbone KM, Rubin SA, Nishino Y, Pletnikov MV