The Relationship between Preventative Shots and Autism - Literature review Example

Preventive Shots and Autism The debate about whether there is a correlation between immunization or preventative shots and diseases such as autism has been going on since 1999. This controversy started when a group of British researchers claimed that children who had been vaccinated for measles also developed intestinal problems. These children also had autism. This caused these researchers to suggest a link between the vaccination for measles, mumps and rubella (MMR vaccination) and autism. Although these researchers retracted this claim years later, the fear of vaccinating their children was left in parents. Despite the amount of research and evidence put forward since then to show the lack of correlation between vaccination and incidence of autism, uncertainty remains among some of the dangers of vaccination. This paper will explore some of the research and reports to examine whether in fact vaccinations in children do cause an increase in the incidence of autism. In 1998 Andrew Wakefield published a paper in the journal Lancet discussing the study by the British researchers claiming that eight of the twelve children immunized developed bowel symptoms and autism spectrum disorder (Taylor, 2006). However Taylor points out that there are a number of other factors that could contribute to the behavior disorders exhibited by these children and that it was almost impossible to confirm that it was in fact the immunization that caused the behavior. This paper was criticized by many people. The American Academy of Pediatrics points out a number of flaws in Wakefield’s study. The sample was small, the vaccinations had been given as many as nine years earlier, data was not objective, and there was no control group. The Academy also reports that Wakefield’s later paper in 2002 was also flawed. This report never-the-less started the controversy about vaccinations and raised the fear of parents to vaccinate their children. Around the same time a report from the California Department of Developmental Services indicated a rise in autism over the years which was later described as an epidemic. (Weber 290). This led to even firmer belief by some parents that there was a connection between the vaccines and autism, although there was still no scientific proof. A substance called thimerosal has been named as the major chemical in vaccinations that cause behavior disorders, especially autism in children. The MMR vaccination is a multidose vaccine and these present potential threats of contamination to children. Thimerosal, was therefore added to vaccines, but at low doses in the 1930s to inhibit the growth of bacteria and fungi and to protect the immunized from infections at the site of the immunization. The problem was that thimerosal is a mecury-based preservative and mercury had been shown to produce adverse effects in the body. Methymercury found in fish and other toxins was causing neurological problems in people when absorbed in high does. However thimerosal contains ethylmercury and not methylmecury which is the form of mercury that is commonly used. There were no existing guidelines for the amount of ethylmercury that is safe for the human body and so the guidelines for methylmercury were used on the assumption, which was false, that the body reacts to both in the same way. The confusion arose therefore that the ethylmercury would be harmful to the body in the same way as methylmercury. The amount of ethylmercury used in the vaccines has been shown to be within the safe levels for the human body. The US Food and Drug Administration (2009) seeks to reassure on the safety of thimerosal. They report studies that examined the levels of mercury in blood and other samples from infants who had been vaccinated. Their results showed that the blood levels were well within safe amounts and they further state that “mercury was cleared from the blood in infants exposed to thimerosal faster than would be predicted for methyl mercury; infants excreted significant amounts of mercury in stool after thimerosal exposure, thus removing mercury from their bodies”. They also confirmed that ethylmercury is metabolized and excreted differently than methylmercury. It has been difficult to prove or disprove this thesis that vaccinations cause increased incidences of autism in children. Research has looked at the issue from many different angles since there are many different factors involved. Nelson and Bauman (2003) examined this link between thimerosal and autism from three different angles. They looked for similarities in children with mercury poisoning and autism. They first looked for commonalities in motor manifestations. The only common motor manifestation they found was in repetitive behavior such as rocking or flapping. Other signs such as hypertension, skin eruptions usually evident in mercury toxicity were not present in autism. They concluded that the “typical clinical signs of mecurism are not similar to the typical clinical signs of autism”. The second angle was to look at the timing of the onset of autism to establish whether it coincides with the immunizations. As they explain, it is very difficult to establish the actual time of onset of autism and to be clear of the environmental effects on onset. The evidence therefore to determine the role of vaccines in autism is inconclusive to them. Thirdly, they questioned the existence of mercury levels in autistic children. No evidence was provided to show significant amounts of mercury in the hair, urine, or blood of autistic children. They also point out that no evidence has been provided to show that chelation therapy led to the improvement in children with autism. These authors question the connection between vaccinations and autism from the fact that mercury has been in the environment for ages. They point out that in the first half of the 20th century medicines containing mercury were used to treat various diseases and even though some children treated with these mercury-containing medicines did in fact suffer from other symptoms, none of them were diagnosed as behavioral symptoms of autism. An additional fact was that reducing levels of mercury in the environment have not coincided with reduced incidence of autism. They referred to a study done in Japan during and after a toxic outbreak in the 1950s and the 1960s. The results showed on the contrary, higher rates of autism in children born between 1966 and 1974 than in the periods just after the outbreaks. This seems to be a global effect, where even though mercury-containing substances are more controlled, yet the level of autism is rising in most parts of the world. Other countries, beside US, have had concerns about vaccinations and autism. Parker et al (2008) reviewed twelve published studies from Denmark, Sweden, UK and US. They were not satisfied that the studies that claimed an association between thimerosal and autism were conclusive. They also pointed out that the elimination of thimerosal exposure did not lead to a decrease in the incidence of autism in Denmark and Sweden. The Public Health Agency of Canada has also been providing information that supports the hypothesis that thimerosal does not cause autism. In their paper, Thimerosal –updated statement (Law and Primeau, 2007) reports by the Immunization Safety Review Committee of the US Institute of Medicine (IOM) in 2001 and 2004 were used as evidence by the Canadian Health Agency in their conclusion that it was not necessary to completely remove thimerosal from vaccines. In 2001 the IOM concluded that "the evidence is inadequate to accept or reject a causal relationship between thimerosal exposures from childhood vaccines and neuro-developmental disorders”. They also believed that “the hypothesis that thimerosal exposure through the recommended childhood immunization schedule [in the US] has caused neuro-developmental disorders is not supported by clinical or experimental evidence." And even more recently in 2004, after examining evidence from studies from Denmark, Great Britain, Sweden and the US, they again concluded that "the evidence favors rejection of a causal relationship between thimerosal containing vaccines and autism." The Canadian Health Agency also provided data from a study in Quebec of 180 children with Pervasive Developmental Disorder to support the lack of association between thimerosal exposure and pervasive developmental disorders (PDDs). Their conclusion was that “There was no correlation between ethylmercury exposure from immunization and the rising prevalence of PDD, the first increase in PDD occurring in 1991 with continued increases in 1997 and 1998 despite complete removal of thimerosal from routinely administered vaccines”. A similar study was carried out in California. Records of children receiving special education services were examined. The incidence of autism was compared over periods of low, high and no exposure to thimerosal. There was no correlation between rise in autism and exposure to thimerosal (Scahill and Bearss 52). The American Academy of Pediatrics presents an important fact to help to convince parents that they should not be afraid to vaccinate their children. According to them there id increasing evidence that autism is determined while the baby is still in the womb. Therefore vaccination cannot be the cause. The difficulty is with the fact that despite the early determination of autism it is only identified at about age one and half years. And this is just about the time that the vaccination MMR is administered. Thus leading parents and others to make the link. .The controversy continued despite so much evidence against it. Researchers at Cambridge Universitys Autism Research Centre, who examined 12,000 children at primary schools in Cambridgeshire between 2001 and 2004 claim that the incidence of autism is at 1 in 58 children, an increase from 1 in 100 children. Even the research team is in disagreement as two suggest a link with the MMR vaccine, while the other members of the team reject the idea. (News-Medical). The two who suggest a link do admit that it could only be a factor in a small sample of children. Other factors have been cited as possible contributors, such as environment, hormones in the womb and genetics. Other events have rekindled the debate. These included a pronouncement about a link by the US presidential candidate John McCain in his campaigning, prime time TV show Eli Stone, and a governmental settlement under the vaccine protection program (Scahill and Bearss 51). There seemed to be more evidence proving that there is no link between vaccinations, and more specifically thimerosal, and occurrence of autism or any other behavioral disorder in children. Weber sums it up in the statement, “A report in 2004 by the Institute of Medicine concluded that there is no association between autism and MMR vaccine, or between autism and thimerosal” She further states that, “there is no conclusive evidence that any vaccine or vaccine additive increases the risk of developing autism” (291). In trying to settle the controversy two main issues were examined in depth. One involved trying to establish empirical evidence to prove a connection between the chemistry of thimerosal and a direct link with autism. The other question arises from the fact that even though thimerosal has been removed from vaccines incidence of autism still continues to rise. As Allen (2005) reports, “The best evidence comes from Denmark, which stopped putting thimerosal in vaccines in 1992; the rate of autism in kids born afterward continued to increase”. Determining the real cause of autism may be the key to settling the debate about whether or not vaccinations contribute to the development of autism in children. The American Academy of Pediatrics states that the autism is thought more frequently as genetically based. They have indicated that abnormalities in brain structures have been identified in people with autism and these abnormalities have developed in the first few weeks of gestation. Also, attempting to explain the rise in cases of autism generally could shed some light on the debate. Allen (2005) discusses some reasons that have been put forward for this including changes in the way autism is diagnosed, new laws expanding federal funding for the care of autistics and greater awareness of parents. The evidence is not enough to prove a link between vaccinations and autism. There are too many other factors that could possibly contribute to the development of autism in children, and too many unanswered questions about the condition itself. Works Cited Allen, Arthur. “Sticking up for thimerosal”. August 2005. Washington Post Newsweek Interactive Co. February 12, 2009. < http://www.slate.com/id/2123647/> American Academy of Pediatrics. n.d. What Parents Should Know About Measles- Mumps-Rubella (MMR) Vaccine and Autism. February 11, 2009. Read More