MMR Vaccine Autism MMR Vaccine

MMR Vaccine Autism

MMR Vaccine and Autism

The MMR vaccine is a three-in-one vaccine which affords protection to children from three hitherto disabling and even fatal diseases like Mumps, Measles and Rubella. This vaccine was considered mandatory for all school age children till the late 1990s when the controversy regarding the connection between MMR and autism erupted. This controversy owed its origins to a paper published by a British doctor in a reputed journal and suggested that there might be an association between administration of MMR vaccine and development of autism. There has been considerable debate over this matter with strong and diverse viewpoints from parents on one hand and the scientific and medical community on the other. Many expert committees from diverse countries have enquired into this matter and a majority of them have rejected any link between MMR and autism. (Rudy, 2009); (Fitzpatrick, 2004)

In 1998, a paper was published in the Lancet which is considered one of the top medical journals of the world. In this paper, Dr. Andrew Wakefield, a British gastroenterologist, suggested that there might be a connection between the MMR vaccines administered during childhood and autism. According to Dr. Wakefield, interaction between the different viruses could adversely affect the immune system of a child resulting in a chronic infection of the gastrointestinal tract. This, in turn, could possibly lead to brain damage as well as autism. (Rudy, 2009); (Fitzpatrick, 2004)

As per Wakefield et al.'s hypothesis, the vaccine initiates a chain of events involving inflammation of the intestine, loss of barrier function or intestinal permeability, discharge of encephalopathic proteins in the bloodstream, and the occurrence of autism. Some other doctors have also demonstrated a link between MMR and autism through different mechanisms. Bernard et al. suggested mercury poisoning as a probable factor behind the development of autism and even proposed a neurochemical basis for the hypothesis. Some doctors have incriminated the use of Thimerisol, a mercury containing preservative used in a number of vaccines, as a probable cause of mercury poisoning resulting in autism. According to these physicians, the quantity of Thimerisol in these vaccines was well above the acceptable limit of 0.1mcg/kg per day, as ruled by the 'Environmental Protection Agency'. Now, mercury is an extremely toxic substance and has been said to be a causative factor in several disease processes which have neurological aspects. (Jacobson; Foxx; Mulick, 2005)

The Wakefield report received widespread media coverage and resulted in a drastic decline in the number of children receiving MMR shots. This obviously caused alarm amongst health officials since these diseases have the potential to create immense health risk for the society. (Jacobson; Foxx; Mulick, 2005) the first appearance of autism is around the same age that children get the MMR vaccines and this coincidence may be one of the factors that have led many parents to suspect the role of MMR in causing the development of autism. However, to prove that this is a mere coincidence and no more, several studies have been conducted to reinforce this viewpoint. (Centers for Disease Control and Prevention, 2008)

Many reputed research institutions including the 'Institute of Medicine' and the CDC or 'Centers for Disease Control and Prevention' have examined several research studies conducted on this issue and have come to the conclusion that there is no definitive proof that a connection exists between the development of autism and administration of the MMR vaccine. The CDC stresses on the point that the initial Wakefield report was "fatally flawed" and that the study which examined only 12 children was too small to make any generalizations about the possible factors that caused autism. Moreover, many of the children under investigation had already shown signs of autism even before the symptoms of bowel disease appeared in them. According to a large study conducted by the 'Danish Medical Research Council' and 'CDC' in November 2002, there was absolutely no link between MMR vaccines and autism. This study which involved over 500,000 children for a period of 7 years and more was published in the "New England Journal of Medicine." (Rudy, 2009); (Centers for Disease Control and Prevention, 2008); (Stratton; Institute of Medicine (U.S.); Board on Health Promotion and Disease Prevention; Gable, 2001)

This particular study compared the rate of occurrence of autism in 96,000 unvaccinated children with the incidence of autism in 440,655 MMR vaccinated children. Their observation was that the rate of incidence of autism was in fact, somewhat higher in unvaccinated children than in MMR vaccinated children. Another case-control study carried out in Atlanta, Georgia, in February 2004, found no evidence of a link between MMR vaccine and autism with enteropathy. Another study conducted by CDC and NIH's 'National Institute of Child Health and Human Development' or NICHD during April 2006 studied data from thirty-one "typically developing children" and 351 children with a cluster of symptoms resembling autism. This study which was published in the "Journal of Autism and Developmental Disorders" did not find any connection between autism and MMR vaccination. Another case-control study conducted from 2004 to 2008 to verify the claims of a previous study which found measles virus RNA in the tissues of the intestine of a particular set of autistic children could not establish a link between the vaccination and autism. This study which could not confirm the claims of the earlier study was published in the Public Library of Science -- PLoS. (Rudy, 2009); (Centers for Disease Control and Prevention, 2008); (Stratton; Institute of Medicine (U.S.); Board on Health Promotion and Disease Prevention; Gable, 2001)

One of the most comprehensive studies was conducted by MRC or United Kingdom Medical Research Council which assessed the results of various studies including the one conducted by Wakefield et al. And did not find any evidence of a link between MMR vaccine and autism. In fact, one of Wakefield's coworkers as well as the Lancet, the journal in which Wakefield's paper was published, admitted that the design of the study was not specific enough to study the association between developmental or intestinal disorders and MMR vaccine. Therefore, such a study which lacked an experimental protocol suitable for specifically targeting such a problem should not be considered as a conclusive evidence for establishing such a link. (Schreibman, 2005)

Fombonne and Chakrabarti conducted a study in 2001 by evaluating groups of patients before and after the years in which MMR vaccination was instituted. They did not find any difference between the age at which the first parental concern for symptoms of autism after the administration of MMR in children appeared and that of children who were not administered MMR. They also observed that the developmental regression rate did not vary before and after the administration of the vaccine. A study conducted by Taylor et al. In 2002 did not observe any change in regression frequency before and after MMR vaccine was instituted in the UK. However, they did find a possible connection between regression and non-specific bowel problems but at the same time, this fact was not related to MMR vaccination in any way. (Bauman; Kemper, 2005)

One particular study which tracked all the 473 autistic children who were born between 1979 and 1998 in various districts of northeast London, found that there was no sharp increase in autism cases after the MMR vaccination program was introduced in 1988. In case, MMR vaccine did cause autism, there should have been an abrupt rise in the incidence of such cases after the institution of this vaccination program. Moreover, this vaccine did not result in the symptoms of autism appearing earlier in children immunized with MMR as compared to children who had not received the vaccination. This research also showed that there was a lack of developmental regression concentrated around the age at which vaccination was given. In fact, the early symptoms of autism are as much likely to appear during the time periods following vaccination as they are during other time periods. (Schreibman, 2005)

One particular retrospective study conducted in California tracked the MMR vaccination program in children born from 1980 to 1994. This study observed that even though there was a significant rise in the number of autism cases reported during this period, it was not accompanied by a corresponding increase in the vaccination rates. A panel of leading scientists at the Institute of Medicine, USA, reviewed a large number of studies on this topic and brought out its final report in 2004. They categorically rejected any connection between the MMR vaccines and autism. (Schreibman, 2005)

Such findings have been found to be quite consistent with many other studies rejecting any link between MMR and autism and have been corroborated by various organizations of considerable repute. These organizations include the "World Health Organization, the American Medical Association, the American Academy of Pediatrics, the Institute of Medicine, the Irish Department of Health and Children and Public Health Branch of Health Canada." (Schreibman, 2005) the most shocking development in this entire debate was the complete turnabout of ten of Wakefield's coworkers who renounced the original study and withdrew their conclusions. This dramatic event followed the revelation that Wakefield had accepted money from lawyers representing parents who had filed lawsuits claiming that the MMR vaccines had caused autism in their children. Some of these children were even part of Wakefield's original study. (Schreibman, 2005)

This disclosure may have laid some doubts to rest but is still not enough to answer the question whether there is actually a link between MMR and autism. Firstly, there is a doubt amongst parents and scientists whether MMR may cause measles, encephalitis or a depression of the immune system in general. However, numerous studies have looked into this possibility and have concluded that the chance is extremely less at the rate of

It is true that there has been a rise in the cases of autism in the U.S. As per CDC data, prevalence of autism in Brick Township, New Jersey, has gone up to 40 per thousand. However, the rise may be attributed to many other factors like small size of population under study, greater awareness of autism and other disorders in the community, higher intensity of case-finding techniques, and the utilization of diagnostic tools like ADOS-G or Autism Diagnostic Observation Schedule-G, which may have resulted in mildly autistic children also being included in the survey. (Stratton; Institute of Medicine (U.S.); Board on Health Promotion and Disease Prevention; Gable, 2001)

An interesting observation was reported in a few studies conducted in Japan. Now, Japan is quite atypical amongst developed nations since its primary source of measles prevention is not MMR. Japan started using MMR only in 1989 but had to withdraw it in 1993 following claims of meningitis cases related to the Urabe mumps strain present in the vaccine. The initial uptake of MMR vaccine in Japanese children born in 1988 was as much as 70% but there was a gradual decline in this rate till 1993. A study conducted by Honda et al. presented a hypothesis that in case MMR vaccine did cause autism, then there should have been a logical increase in the number of autism cases after 1989 when MMR was introduced followed by a gradual decline in reported cases of autism after 1993 when MMR was withdrawn. The area under study had good diagnostic practices and advanced services for identification of developmental delays. The researchers found that cases of autism continued to rise in the period under study irrespective of the fact that MMR was withdrawn. Obviously, MMR vaccination was not to blame for the rising cases of autism. Of course, apart from the Wakefield report, there have been other studies which have reportedly found an association between MMR and autism. However, many of such studies have been found to have methodological flaws or some biases. (Jepson; Johnson, 2007)