Vaccines And Autism Essay

Choose from the following topics: 1) vaccines and Autism, 2) vitamin D deficiency and multiple sclerosis, 3) aluminum and Alzheimer’s disease, 4) the cow’s milk diet to reduce weight, 5) circumcision to prevent sexually transmitted diseases, 6) moderate hypothermia after cardiac arrest to reduce neurological damage, or 7) the ketogenic diet to treat epilepsy. Present both “supporting” and “refuting” evidence. Minimum 150 words and two peer-reviewed references initial post. Minimum 100 words reply and one peer-reviewed reference. Must be published within the last five years (no older than 2015). CANNOT be a blog, WebMed, or anything that is not scholarly and peer-reviewed (meaning it cannot be from FORBES, National Geographic, etc…)Vaccines And Autism Essay

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In 1998, Andrew Wakefield and colleagues published a paper in the journal Lancet. Wakefield’s hypothesis was that the measles, mumps and rubella (MMR) vaccine caused a series of events that include intestinal inflammation, entrance into the bloodstream of proteins harmful to the brain, and consequent development of autism. In support of his hypothesis, Dr. Wakefield described 12 children with developmental delay — eight had autism. All of these children had intestinal complaints and developed autism within one month of receiving MMR.Vaccines And Autism Essay

The Wakefield paper published in 1998 was flawed for two reasons:

About 90% of children in England received MMR at the time this paper was written. Because MMR is administered at a time when many children are diagnosed with autism, it would be expected that most children with autism would have received an MMR vaccine, and that many would have received the vaccine recently. The observation that some children with autism recently received MMR is, therefore, expected. However, determination of whether MMR causes autism is best made by studying the incidence of autism in both vaccinated and unvaccinated children. This wasn’t done.
Although the authors claim that autism is a consequence of intestinal inflammation, intestinal symptoms were observed after, not before, symptoms of autism in all eight cases.
This study was subsequently retracted; in scientific terms, this means that the paper is not part of the scientific record because it was found to be based on scientific misconduct. In this case, the studies were deemed fraudulent and data misrepresented.Vaccines And Autism Essay

Second study
In 2002, Wakefield and coworkers published a second paper examining the relationship between measles virus and autism. The authors tested intestinal biopsy samples for the presence of measles virus from children with and without autism. Seventy-five of 91 children with autism were found to have measles virus in intestinal biopsy tissue as compared with only 5 of 70 patients who didn’t have autism. On its surface, this was a concerning result. However, the second Wakefield paper was also critically flawed for the following reasons:

Measles vaccine virus is live and attenuated. After inoculation, the vaccine virus probably replicates (or reproduces itself) about 15 to 20 times. Measles vaccine virus is likely to be taken up by specific cells responsible for virus uptake and presentation to the immune system (termed antigen-presenting cells or APCs). Because all APCs are mobile, and can travel throughout the body (including the intestine), it is plausible that a child immunized with MMR would have measles virus detected in intestinal tissues using a very sensitive assay. To determine if MMR is associated with autism, one must determine if the finding is specific for children with autism. Therefore, children with or without autism must be identical in two ways. First, children with or without autism must be matched for immunization status (i.e., receipt of the MMR vaccine). Second, children must be matched for the length of time between receipt of MMR vaccine and collection of biopsy specimens. Although this information was clearly available to the investigators and critical to their hypothesis, it was specifically omitted from the paper.Vaccines And Autism Essay
Because natural measles virus is still circulating in England, it would have been important to determine whether the measles virus detected in these samples was natural measles virus or vaccine virus. Although methods are available to distinguish these two types of virus, the authors chose not to use them.
The method used to detect measles virus in these studies was very sensitive. Laboratories that work with natural measles virus (such as the lab where these studies were performed) are at high risk of getting results that are incorrectly positive. No mention is made in the paper as to how this problem was avoided.
As is true for all laboratory studies, the person who is performing the test should not know whether the sample is obtained from a case with autism or without autism (blinding). No statements were made in the methods section to assure that blinding occurred.

What vaccines do: the science at the heart of a controversy.
When a pathogen [7], such as harmful bacterium or virus, infects the body for the first time, the immune system [8] will quickly recognize it as an “invader” based on molecular features specific to the pathogen (known as antigens) (Figure 1A). In response to these antigens, the body produces molecules called antibodies [9] that enable our immune system to track down and kill the pathogen.Vaccines And Autism Essay

The first time the body encounters a pathogen, it takes days to assemble enough antibodies to defeat the infection. In that time, the pathogen has the opportunity to attack the body, causing us to experience symptoms of illness. After this first encounters, the body will memorize what the antigens look like, so that if the same pathogen strikes again, we will be able to launch a stronger, faster defense against future invasions.

Vaccines teach the body to recognize a pathogen. Specifically, vaccines contain the same antigens as pathogens (Figure 1B), but in a weakened or dead form, so that the body can learn what the pathogen looks like and produce antibodies (Figure 1C) in a safe and comparatively controlled manner. Thus, when the body encounters the real pathogen, it is already trained and ready to eliminate the pathogen before it can do any damage (Figure 1D).Vaccines And Autism Essay

Importantly, a vaccine protects not only the individual to whom it is administered, but also the entire population. When the number of immunized individuals within a population reaches a critical threshold, herd immunity [10] is conferred (Figure 2). Herd immunity protects the entire population, even those who are not vaccinated are protected from disease. The percentage of the population that must be immunized to achieve herd immunity varies for individual diseases, with thresholds for common diseases ranging from 75-94% [11]. Herd immunity is crucial to protecting those who are not eligible for vaccines, such as infants, pregnant women, and immunocompromised adults. This means that while vaccines may seem like a personal choice, vaccination protects the entire population—and accordingly, failure to vaccinate could have negative population-level consequences.

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Figure 1: Building immunity through vaccination. (A) Pathogens such as bacteria and viruses have molecular signatures called antigens (green triangles) that can be recognized by the body’s immune system. (B) Vaccines contain these antigens (or parts of them), without the dangerous parts of the pathogen that cause disease. (C) Upon injection of the antigens into the body, our immune systems generate antibodies (Y-shapes) which recognize the antigen. (D) If an infection by the same pathogen occurs in the future, the immune system already has antibodies at the ready. The body can rapidly recognize the pathogen based on its antigen and launch a fast, effective defense.Vaccines And Autism Essay
Are vaccines truly that effective?
Though no vaccine is 100% effective, many come quite close. For instance, two doses of the chickenpox vaccine are 98% effective against any form of chickenpox [12]. In fact, many vaccines against deadly diseases – such as smallpox [13], yellow fever [14], measles [15]- are over 95% effective, as long as they are administered on schedule. History has also attested to the effectiveness of vaccines. Immediately following the licensing of the measles vaccine in 1962, the number of measles cases in the US dropped dramatically [16] (Figure 3).

Figure 2.: Herd immunity. (A) When no one in a population is vaccinated, infections can spread rapidly and become an outbreak. (B) When some individuals are vaccinated, they are individually protected from an infection. However, if the number of people vaccinated is below the critical threshold for herd immunity, the infection can still spread. (C) When a large enough proportion of the population is vaccinated, herd immunity is conferred. Outbreaks are prevented from spreading, and individuals who are unvaccinated are still protected.Vaccines And Autism Essay
Some anti-vaccinationists have claimed that the decrease in measles shortly after the vaccine was introduced is purely coincidental, and that other measures, such as improved hygiene and sanitation, are mainly responsible for the decline in measles and other than diseases. If this were true, we would expect all diseases to have begun their most drastic declines around the same time. However, the sharpest drop in polio cases occurred shortly after the licensing of the polio vaccine in 1955 [17], in the late 50’s — years before the measles decline occurred (Figure 2). Similarly, cases of rubella declined sharply after 1969 [18], when the vaccine was first licensed (Figure 3).

The observation that a decline in the number of disease cases occurs right after the introduction of the vaccine for that disease argues very strongly that it is, indeed, the vaccine which is responsible for the reduction in disease. While improvements in sanitation and healthcare were doubtless beneficial, the availability of vaccines was still the major determinant of the spread of a disease. Vaccines And Autism Essay