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Vaccines and Autism: Is there a connection?
In the past decade there has been a great deal of controversy in the scientific and medical communities over the proposed correlation between the administration of the Measles-Mumps-Rubella vaccine to children and the development of autism. The idea of a connection between childhood vaccines and autism has only come to light in recent years after there were a small number of individual cases that suggested that such a link might be possible. The general public reacted strongly to the suggested link with a number of “anti-vaccination” initiatives springing up nearly overnight. If such a link between vaccines and autism were found to be accurate, it would have a vast effect on the world’s disease prevention programs. The purpose of this paper is to evaluate the association between the Measles-Mumps-Rubella vaccine and Autism Spectrum Disorder.
The first vaccinations were developed in the 1700s. The most successful initial vaccination was administered by Edward Jenner in the 1770s. He inoculated an 8-year old boy with pus from the hand of a milkmaid who had been infected with cowpox, a disease that is similar to smallpox but has a very mild effect in humans. Afterwards he observed that the boy did not catch smallpox, and the first instance of immunity was observed. Later Louis Pasteur generalized Jenner’s idea by creating vaccinations against rabies in 1885. Vaccines work by introducing the weakened form of a disease into a person’s bloodstream. The body produces proteins called antibodies that are responsible for fighting off antigens. Since the antigens introduced from vaccines are weak they typically don’t cause a person to be sick. After the disease is fought off the antibodies die but memory cells are created that can reproduce the antibodies. The vaccination causes a person to develop immunity to the disease, so if their body is exposed to the disease again the original antigen’s memory cells will be able to reproduce the antibodies and effectively fight off the disease without the person becoming seriously ill.
The widespread usage of vaccinations around the world is one of the most important innovations in modern medicine. As direct result of immunizations, the rates of many once common diseases have decreased in both developing and non-developing countries. Smallpox and poliomyelitis (polio) have both been completely eradicated as a result of public health initiatives that focused on the immunization of people worldwide. According to the Centers for Disease Control and Prevention, vaccines are important, not just for preventing individuals from becoming sick, but also from preventing widespread infections of entire populations, an idea referred to as herd immunity. If the vaccination rate of a population drops too low an outbreak of the disease is much more likely to occur, and the disease can be spread through the population much more easily.
According to the Autism Society of America, “Autism is a complex developmental disability that typically appears during the first three years of life and affects a person’s ability to communicate and interact with others.” Autism affects about 1 in every 150 births meaning about 1.5 million Americans today have some form of autism. Autism is classified as a Pervasive Developmental Disorder (PDD) along with Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS), Asperger syndrome, Rhett syndrome, and Childhood disintegrative disorder (CDD). All Pervasive Developmental Disorders are characterized by impairment in one or more areas of development, such as communication and social skills. Autism is a spectrum disorder that can exist in individuals as any combination of a number of symptoms, including difficulty interacting in social situations and learning difficulties.
There has been much speculation about the cause of autism. It is thought that a combination of both environmental and neurological factors contributes to the onset of autism in young children. While there is no cure for autism, those affected can improve their quality of life through a number of intervention and treatment programs. A major goal for treatment programs is to teach autistic individuals functional independence and communication skills. Early diagnosis of autism in children is key for beginning treatment early. There is no specific test that is used to diagnosis autism, but rather a diagnosis is made by a trained professional after observing a child’s behavior and running a number of diagnostic tests to assess neurological development, behavioral tactics and communication skills.
A Possible Connection?
The Measles-Mumps-Rubella vaccine is a mixture of 3 attenuated viruses that is administered by infection so that a body can build up immunity to measles, mumps and rubella, three illnesses that caused numerous deaths in both children and adults before the vaccines became widely available. The first dosage of the MMR vaccine is usually administered around a child’s first birthday and the second dosage around the time the child turns four of five. The immunity lasts for a lifetime with no required booster shots. After the second dose, 99.7% of people will have developed immunity. Most children who receive the vaccine do not show signs of any adverse side effects. Only a small portion (about 20%) reacts negatively, and most of these reactions are very mild, such a rash or low grade fevers. Any side effects cause by the MMR vaccine are largely due to the measles vaccine that it contains. Only in very rare cases will children display any serious negative consequences after receiving the vaccine.
It has recently been postulated that there is a possible link between the administration of the Measles-Mumps-Rubella vaccine to children and the development of a number of serious negative side effects, including gastrointestinal problems, regression, and autism. An initial article postulating a link was published in 1998 by Dr. AJ Wakefield. After the article was published a number of personal testimonials began to appear in newspapers and on websites in the mid 1990’s regarding instances of children who had shown extremely adverse reactions that presumably resulted from the MMR vaccine. One example is the story of Eric Gallup, as told by his mother. “Eric Gallup was born on January 17, 1985. He was normal at birth and received all his vaccines on schedule including the measles-mumps-rubella (MMR) vaccine on April 28, 1986. He was progressing but after receiving the MMR vaccine, his speech and cognitive skills deteriorated.” (Australian Vaccination Network) Articles like this sparked a controversy over whether or not it was safe to vaccinate children. Many parents argued that since the diseases were nearly nonexistent anyway it was not necessary to vaccinate their children and risk such negative side effects.
Evaluation of Literature
In 1998 Dr. AJ Wakefield published an initial paper that studied a group of 12 children who has lost acquired developmental skills suddenly at a young age and developed a number of gastrointestinal problems, including diarrhea and chronic abdominal pain. After gathering information from the parents of the children in the study Wakefield determined that the children’s symptoms had begun to develop after they had received the MMR vaccine. According to paper, “We have identified a chronic enterocolitis in children that may be related to neuropsychiatric dysfunction. In most cases, onset of symptoms was after measles, mumps, and rubella immunization.” (Wakefield et al., 1998) The uproar caused by this article happened almost immediately. For centuries vaccines had been considered one of the most notable medical advancements in history, but now a study was being presented that claimed that the benefits of immunization might be outweighed by the devastating consequences it could cause.
In response to Dr. AJ Wakefield’s 1998 study a large number of follow up studies have been conducted in the effort to support or refute his findings. In 2001 two British researchers conducted a study using the data of 96 children who were born between 1992 and 1995 and had been diagnosed with a pervasive developmental disorder. They hoped to determine whether or not there was a new phenotype of autism that was connected to a measles infection caused by the vaccine and that resulted in children showing signs of regression and gastrointestinal problems. They determined that “No evidence was found to support a distinct syndrome of MMR-induced autism or ‘autistic enterocolitis’.” (Fombonne & Chakrabarti, 2001)
A retrospective cohort study was conducted by Kreesten Meldgaard Madsen that included 537,303 participants, all children born in Demark from January 1991 to December 1998. Of the participants, 316 were diagnosed with autistic disorder, and 422 others were diagnosed with some other autism spectrum disorder. It was determined that “There was no association between the age at the time of vaccination, the time since vaccination, or the date of vaccination and the development of autistic disorder.” (Madsen et al., 2002). Studies such as this one, and numerous others that have been conducted, provide much more statistically sound data than the original investigation that had been conducted by Wakefield. Because the Madsen study surveyed more than half a million participants, it has more statistical power than the Wakefield paper, which only included 12 participants.
Another full population study was published in 2005; it was conducted in Japan, a country where use of the MMR vaccine has been terminated. The study’s participants included around 300,000 children who had been born between 1988 and 1996. Although the MMR vaccination rate declined sharply from 1988 to 1993 and no vaccinations were administered after 1993, the study found that the rate of diagnosis of autism spectrum disorder in children remained fairly constant. If the claims that the MMR vaccine play a role in the cause of autism had been accurate, the rate of autism spectrum disorder diagnosis should have decreased as administration of the vaccine ceased. They concluded that “…MMR vaccination is most unlikely to be a main cause of ASD, that it cannot explain the rise over time in the incidence of ASD, and that withdrawal of MMR in countries where it is still being used cannot be expected to lead to a reduction in the incidence of ASD.” (Honda, Shimizu, & Rutter, 2005)
As a reaction to the number of follow up studies, a paper was published in 2004 by the coauthor of Wakefield’s 1998; this retraction was published in the same journal as Wakefield’s original paper. The new article served to retract the connection between the MMR vaccine and autism that had been postulated in 1998. The retraction was made by 10 of the original 12 others and stated that the remaining two could not be contacted. The paper stated “We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism as the data were insufficient… we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper, according to precedent.” (Murch et al., 2004). While it is not possible to totally disprove the theory that the MMR vaccine can be linked to the development of autism based on numerous studies and published papers, there is no apparent connection.
Evaluation of Web Resources
A number of resources are available on the World Wide Web that provide information about the connection between vaccines and autism. The two major types of websites found on the subject are either ones provided by governmental and scientific organizations that detail accurate information about vaccines and their side effects and those less verifiable websites that consist mainly of personal accounts that are not supported by concrete scientific evidence.
Reputable resources on the topic of vaccines and autism include websites such as the National Network for Immunization Information, the Autism Society of America, the American Academy of Pediatrics, the National Institute of Health, and the Centers for Disease Control and Protection. The motive of these types of websites is to educate the general public about the importance of vaccinating children. Because the scientific and medical communities hold the belief that vaccines are not connected to the development of autism, these websites are focused on encouraging parents to vaccinate their children at the appropriate age for the benefit of both the individual child and the population as a whole. Reputable websites provide reliable information based on factual scientific knowledge that is backed up by tangible evidence and supported by doctors and researchers. These websites claim that because numerous scientific studies have shown no correlation between vaccines and autism all children should be vaccinated. When people are searching for information on vaccines, autism, or the connection between them, the most accurate information can always be obtained from these types of websites.
The second type of websites on the Internet that address the connection between vaccines and autisms are of a less reputable variety. There are a number of other websites that provide victim testimonies and “horror stories” about individual children who have shown severe adverse reactions to vaccinations. These websites are not reliable because they are testimonies of individuals, so they are not usually scientifically accurate, cannot be proven to be true, and are nearly impossible to be made applicable to other individuals. The rationale behind the claims made on these websites is that vaccines cause such horrible reactions in children that they are not worth the risk, thus children should not be vaccinated. They claim that vaccinations must cause autism and other problems, even though the occurrence might be purely coincidental. Most of these types of websites are directed towards parents and are focused on encouraging them not to vaccinate their children, despite the advice of their children’s doctors.
Based on a number of clinical and epidemiological research studies that have been conducted over the past decade, there is no outstanding evidence to suggest that the Measles-Mumps-Rubella vaccine plays a role in the development of autism, autism spectrum disorder, or gastrointestinal problems in young children. Any relationships between the MMR vaccine and the aforementioned conditions are primarily casual, and parents, caregivers and medical personnel should work to ensure that every child is vaccinated at the appropriate age.
(n.d.). American Academy of Pediatrics: Childhood Immunization Support Program.
Retrieved from http://www.cispimmunize.org/index.html
(n.d.). Australian Vaccination Network: Children's Gallery Vaccine Injured. Retrieved
(n.d.). Autism Society. Retrieved from http://www.autism-society.org/
(n.d.). Centers for Disease Control and Prevention: Vaccines & Preventable Diseases.
Retrieved from http://www.cdc.gov/vaccines/vpd-vac/default.htm
Fombonne, E., & Chakrabarti S. (2001). No evidence for a new variant of measles
mumps-rubella-induced autism. Pediatrics, 108(4).
Honda, H., Shimizu, Y., & Rutter, M. (2005). No effect of MMR withdrawal on the
incidence of autism: a total population study. Journal of Child Psychology and
Psychiatry, 46(6), 572-579.
Madsen, K.M., Hviid, A., Vestergaard, M., Schendel, D., & Wohlfahrt, J., Thorsen, P., et
al. (2002). A population-based study of measles, mumps, and rubella vaccination
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Murch, S.H., Anthony, A., Casson, D.H., Malik, M., & Berelowitz, M., Dhillon, A.P., et
al. (2004). Retraction of an interpretation. The Lancet, 363(9411), 750.
(n.d.). National Institute of Neurological Disorders and Stroke: Autism Fact Sheet.
Retrieved from http://www.ninds.nih.gov/disorders/autism/detail_autism.htm
(n.d.). National Network for Immunization Information: Vaccine Information. Retrieved
Wakefield, A.J., Murch, S.H., Anthony, A., Linnell, J., & Casson, D.M., Malik, M., et al.
(1998). Illeal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive
developmental disorder. The Lancet, 351(9103), 637-641.
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