The following essay is one I wrote for my IB 35AC class last semester that I am really proud of.
Measles is a highly contagious, airborne disease that has plagued history for many centuries. Before measles vaccinations were widely used, “measles caused an average of 100 deaths per year” in the United Kingdom (Jansen et al., 2003). In early 2014, two UC Berkeley students with measles exposed individuals living in the Bay Area to the disease and drew attention to the question: should everyone be vaccinated against measles? The effectiveness of the measles, mumps, and rubella vaccine (MMR) in providing immunity to measles and how vaccinating the majority of the population can reduce the number of cases of measles suggests that the affirmative viewpoint is the most logical. Those who oppose this viewpoint do so mainly on the grounds that some studies have been published that report a correlation between the MMR vaccine and the development of autism.
Measles is caused by a virus and is very contagious because of its ability to be transmitted through the air. Symptoms of measles include fever, cough, rash, and Koplik’s spots, which are white spots that “appear on the buccal mucosa… and occasionally on the soft palate, conjunctiva, and vaginal mucosa” (Perry et al., 2004). However, it is the complications that arise from measles that typically lead to hospitalization and death. Some complications include otitis media, which is characterized by the inflammation of the Eustachian tube in the ear, croup, pneumonia, encephalitis, which is characterized by the inflammation of the brain, diarrhea, pink eye, and keratitis, which is characterized by the inflammation of the cornea (Perry et al., 2004). Typically, individuals less than five years of age, older than 20 years of age, and immunosuppressed individuals will more likely experience complications as a result of measles (Perry et al., 2004). The complications are defense mechanisms that the human body uses to signify that something is wrong and that the body is trying to defend itself against either a pathogen or injury (Schmitt, 2014). Vaccination is important in minimizing the spread of the disease to those who are most vulnerable.
When the MMR vaccine was made available in the United Kingdom in 1988, its effectiveness against measles was seen in the form of the decrease in the number of cases of measles reported relative to the increase in vaccine uptake (Jansen et al., 2003). After 1998, research into the side effects of the MMR vaccine resulted in a decrease in vaccine uptake in the United Kingdom (Jansen et al., 2003). As a result the reproductive number (R), or the average number of individuals an infected individual infects, “for the years 1995-1998 and 1999-2000 were R=0.47 and R=0.82, respectively” (Jansen et al., 2003). The smaller the difference between one and the reproductive number, the more likely large outbreaks of the disease will occur; once the reproductive number is greater than one, the disease can be classified as an endemic (Jansen et al., 2003). This data correlates to the finding that “vaccination protects >90% of recipients against disease” (Perry et al., 2004). The MMR vaccine is a biological and technological advancement that has been proved to increase the fitness of the members of society.
The benefit of increased vaccine uptake can be affiliated with the concept of herd immunity. This idea entails that if a large number of people are immunized against a particular disease, a large outbreak is less likely to ensue. The mechanism behind this idea is that if the majority of individuals in a population are immune to a certain disease, the less likely it will be that the individual will contract the disease and pass it on to another. The herd immunity threshold (%), or “the minimum proportion to be immunized in a population for elimination of infection,” is a quantitative way to measure this concept (Fine, 1993). Under ideal conditions, the herd immunity threshold for measles should range from 83-94% (Fine, 1993). It is important to recognize that the herd immunity threshold varies from community to community because individuals only interact with other individuals in their individual community, but at some point the number of individuals vaccinated in a community will significantly reduce or eliminate the presence of the disease. Generally, if the majority of members of a community are vaccinated for measles, the less likely measles will become an endemic.
There are some parents that refuse to vaccinate their children based on a series of studies that were published that established a connection between the development of autism and the MMR vaccine. Anti-vaccine activists such as actress Jenny McCarthy encourage the allegation that the MMR vaccine causes autism. On April 1, 2009, the New York Times published McCarthy’s statement, “If you ask a parent of an autistic child if they want the measles or the autism, we will stand in line for the f*cking measles” (Kluger, 2009). This only made parents panic and put off the vaccination of their children against measles, mumps, and rubella, which can lead to harmful effects in infants. One such publication released in 1998 by The Lancet, a medical journal, reported that there is a connection between the development of autism and the MMR vaccine. It stated that autistic behavior was apparent anywhere from hours to months after the MMR vaccine was given to 12 children (Wakefield et al., 1998).
Most of the publications connecting the development of autism and the MMR vaccine have since been retracted on the basis of incorrect assessments. The main point of confusion for most of these studies was that children often start to display the behavioral symptoms of autism around the same age they are eligible to receive the MMR vaccine. Since the retraction of these publications, new studies have since been conducted to further disprove the connection between the development of autism and the MMR vaccine. One publication of these studies reports that in the “five cohort studies involving 1,256,407 children” the odds ratio for autism and MMR was 0.84 (Taylor et al., 2014). Odds ratio (OR) is a quantitative “measure of association between an exposure and an outcome” (Szumilas, 2010). If the OR is less than 1 then there is little to no association between the exposure and outcome (Szumilas, 2010). Thus, these studies further disprove the claim that there is a relationship between the development of autism and the MMR vaccine. It is also important to consider the effect of delaying vaccination in young children. Not only is the child susceptible to the disease after maternal antibodies that provide natural immunity to certain disease no longer protect the child, “herd immunity effect [is] greatest when vaccination occurs at earliest possible age” (Fine, 1993). In order to ensure that herd immunity works in favor of decreasing the spread of disease, children must be vaccinated as soon as maternal immunity diminishes.
There is no evidence that suggests that the development of autism and the MMR vaccine are interrelated. The unwillingness of parents to vaccinate their children is in effect not allowing herd immunity to take place in order to keep that majority of society from contracting measles. The effectiveness of the MMR vaccine has been repeatedly tested and confirmed, so the indisposition to utilize the technology available to parents to keep their children and society healthy is really just a matter of misinformation. The vaccine is effective in preventing the majority of measles cases and spurs the development of herd immunity; thus it should be utilized.
Fine PEM. 1993. Herd immunity: History, theory, practice. Epidemiol Rev 15(2):265-302.
Jansen VAA, et al. 2003. Measles outbreaks in a population with declining vaccine uptake. Science 301:804.
Kluger J. 2009 Apr 01. Jenny McCarthy on Autism and Vaccines [Internet]. Time Inc.; [cited 2014 Oct 25]. Available from: http://content.time.com/time/health/article/0,8599,1888718,00.html
Perry RT, and Halsey NH. 2004. The clinical significance of measles. J Infec Dis 189(Supp1):S4-S16.
Schmitt CA. 2014. Class #17: Evolutionary Medicine. IB35AC: Human Biological Variation. October 23.
Szumilas M. 2010. Explaining Odds ratio. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 19, 227–229
Taylor LE, Swerfdeger A, and Eslick GE. 2014. Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies. Vaccine 32:3623-3629.
Wakefield AJ, et al. 1998. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 351:637-641. RETRACTED.