Vaccines & Autism: A Critical Review Of Recent Scientific Controversy

Do vaccines cause Autism?

The assignment is about any recent scientific controversy critical review.

Background on Vaccines

Vaccines are the biological tools used for acquiring active immunity against a wide range of diseases, and presently research is going on across the world to bring remarkable advancements in this field (Healer and Cowman 2016). Controversies regarding vaccines are coming in the limelight in recent times against the advanced scientific research and their wider application in the field of medical science. Though vaccines have been found to be beneficial extensively in against different diseases, opponents have questioned the safety, effectiveness and necessity of a wide range of recommended vaccines. This pool of scholars has the opinion that mandatory vaccines are often found to violate individual rights to religious principles and medical decisions. In similar context, a substantial pool of literature indicates that vaccines lead to some diseases, such as autism (Ahmed et al. 2016). Whether vaccines lead to autism is a significant topic of debate in the present world and is guided by many studies attempting to find a suitable answer to the question. The link between vaccines and autism is constantly drawing the attention of researchers who have the aim of making vaccine application safer for the community at large (Jain et al. 2016). The present review aims to critical analyse whether vaccines lead to autism. The review would be based upon a wide range of important literature and attempt to draw a logical conclusion from the analysis.

A vaccine is an agent resembling a disease-causing microorganism and is made from the killed or weakened form of the same organism. The agent works by stimulating the immune system of the body for recognising the agent and triggering responses against it and generating immune system recognition ability. Vaccines can be administered through injections, mouth or by aerosol. Vaccination refers to the injection of the organism producing immunity in the body against the particular organism. The primary purpose of using vaccines is to save lives through prevention of disease outbreaks and protection of those not for whom vaccination might not be done. Vaccines can be of two forms- therapeutic or prophylactic (Callaway 2017). The most commonly formed vaccines include those against HPV, chicken pox, influenza, measles, pumps and rubella. As per the reports of World Health Organisation (WHO), vaccines are presently under use for prevention and control of as many as twenty-five infections (MacDonald 2015). Opposition to the use of vaccines has come up from an extensive source of critics that have emerged since long back. Though the benefits of vaccines in preventing diseases, serious in nature, have been established, adverse impacts of vaccines have also created the base for further research opposing the use of vaccines (Wexler and Coalition 2016).  

Background on Autism

Autism is a neurodevelopmental disorder whereby an individual suffering from it develops impaired verbal and non-verbal communication, social interaction and repetitive and restricted behaviour (Brunsdon and Happé 2014). Autism is noticed in children within the first two years of life and the signs then gradually develop. The underlying diagnostic criteria need the significant symptoms to be apparent within three years of age. Autism is caused by a combination of environmental and genetic factors. Symptoms of autism are the result of maturation changes in the brain, and the mechanism can be best understood by understanding the pathophysiology of structures of the brain and neuropsychological links between behaviours and the brain (Boutot, 2016). In the DSM-V, autism is included within the autism spectrum disorders (ASDs), delaying cognitive development as well as language development (Daniels and Mandell, 2014).

The “Wakefield” studies carried out in the year 1998 by Andrew Wakefield, and fellow researchers hypothesised that measles-mumps-rubella vaccine (MMR) vaccines led to the development of Autism Spectrum Disorder (ASD) in individuals. The study had the hypothesis that MMR vaccine is responsible for an array of events including reduced function of the intestinal barrier, increased intestinal inflammation, entry of  encephalopathic proteins into the blood stream, and consequential progress of autism. To support the hypothesis, Wakefield studied a total number of 12 children with neurodevelopmental dealy, of which 8 had autism. All of them suffered gastrointestinal complaints and were found to be developing autism within one month after getting the vaccine for MMR. Many individuals developed the belief that certain hazardous consequences arise from vaccinating the children and these consequences are fatal (Colaizzo 2016).  

Deisher et al. (2014) investigated the previously overlooked environmental factors such as childhood vaccines leading to autism with dose-effect evidence and action mechanisms. A cohort study was conducted with worldwide population. Settings of Western Australia, United States, Denmark and the United Kingdom were used. The results of the study indicated that rising prevalence of autistic disorder had a direct relation to vaccines that are produced using human fetal cells.

DeLong (2011) had found a positive relationship between childhood vaccination and autism prevalence. The study conducted was across the US population. The authors stated that the reason for the rise of autism in the United States began in the 1990s. Environmental factors trigger the development of autism, and one such factor might be vaccination in young children. With the help of regression analysis and controlling ethnicity and family income, the researchers determined the association between the proportion of children receiving vaccines by age two years and the prevalence of autism (AUT) in each U.S. state from the time frame of 2001 to 2007. The study found a statistically significant relationship. A higher proportion of children receiving vaccination led to the higher prevalence of autism. The results of the study had the inference that though mercury had been removed from the vaccines, other elements of vaccines might lead to autism.

Link Between Vaccines and Autism

Geier et al. (2008) had stated that ASD might result from a combination of biochemical or genetic susceptible factors, such as exposure to mercury (Hg) at critical developmental stages. Mercurials have been found in drugs and vaccines and are known to cause dysfunction of sensory, neurological, immune, behavioural and motor systems that are similar to traits associated with autism. Reviews of molecular mechanisms of impact of mercury in body functioning indicate that exposure to Hg can possibly induce damage to the brain and consequent death in a manner similar to autism. Reviews of treatment have suggested that patients suffering from ASD undergoing treatment for reducing Hg have shown remarkable clinical improvements in a number of cases. Therefore the overpowering predominance of evidence suggested that Hg exposure through vaccine can lead to autism.

Though a considerable source of literature exists that indicates autism has no link with vaccination, many studies also exists that opposes this viewpoint and strives to justify that vaccines are not safe to the maximal extent. Jain et al. (2015) had stated that in spite of research indicating no connection between the measles-mumps-rubella (MMR) vaccine and autism spectrum disorders (ASD), there exists a belief that vaccines lead to autism. The result of such belief is a drastic lowering of vaccination level. The researchers conducted a study to report the occurrence of autism after MMR vaccination in a large population sample in US children having older siblings with or without autism. A retrospective cohort study was carried out using an administrative claims database related with a large commercial health plan. Out of 95727 children with older siblings, 994 (1.04%) were found to be diagnosed with autism. On the other hand, 1929 (2.02%) children had an older sibling wth autism. Out of those children who had older siblings with autism, 134 (6.9%) had autism whereas 860 (0.9%) children had unaffected siblings(P < .001). It was therefore concluded that in the large sample of children having older siblings, receiving MMR vaccine had no relation with increased chances of developing autism. This fact was true regardless of whether their older siblings had autism. The findings indicated that there was an absence of harmful association between MMR vaccine and autism among children who are already at higher risk of autism.

Uno et al. (2015) carried out a case-control study to investigate the association between the risk of Autism Spectrum Disorder (ASD) onset, and exposure to MMR vaccine and consumption of thimerosal measured from vaccinations. The study was carried out with a highly genetically homogenous population in Japan. The results indicated that there were no statistically significant differences in the MMR vaccination and thimerosal dosage between controls and cases at any age. Moreover, the Odds Ratio 995% CIs) of MMR vaccination and thimerosal dosage associated with ASD had no significant differences in the conditional multiple regression models. The study, therefore, concluded that there was no convincing evidence that MMR vaccination was a causal factor for the onset of ASD.

Studies Opposing Link Between Vaccines and Autism

Taylor, Swerdfeger and Eslick (2014) attempted to prove that vaccines have no relation with autism. As per the authors, there is an enormous debate regarding whether there is a possible link between vaccinations taken in childhood and subsequent autism development. The researchers carried out a meta-analysis with the aim of summarising the available resources from cohort studies and case-control studies on databases of PubMed, MEDLINE, EMBASE, Google Scholar. Findings of the meta-analysis suggested that vaccinations did not have any association with the development of autism. In addition, multiple vaccines such as MMR or the different components of vaccines (mercury or thimerosal) also did not have any association with autism. The scientific evidence might be overwhelming, indicating that there is no link between autism and vaccine. Most of the common population are keen on vaccinating their children as per the set schedules. However, the risk to the public remains in a manner that is difficult to define even if scientific explanations come up.

Goin-Kochel et al. (2016) had highlighted through a study that there is no major link between autism and vaccination. Receipt of six vaccines was compared across different patterns of onset of autism. Vaccine receipt was similar amongst all autism-onset groups apart from varicella. It was found that those participants with delay-plus-regression onset exhibited lower rates of varicella receipt. Mean rates of receipt of varicella lowered within the equivalence range. The findings did not support autism to be caused by the vaccine.

There is an immediate need for further research for gaining in-depth knowledge about whether vaccines lead to autism. Insights into the topic would prove to be the foundation for bringing reforms in the manner medical intervention is provided. This step would be significant for achieving better health outcomes for the whole community (Novella 2016). Since the possibility of involvement of vaccination in the development of autism cannot be ruled out at any cost, further investigations are required at molecular, cellular, genetic and immunological levels. This approach would allow the researchers to unravel the immunopathogenic mechanism linked with processes of autism development in the brain. This would certainly open up a wide range of avenues guiding the prevention and cure of the devastating neurodevelopmental disorder.

Conclusion 

Since the discovery of vaccines in the 20th century, healthcare providers across the world in the 21st century have experienced negative impacts of the vaccine due to the devastating emergence of diseases such as autism and rubella. Fear of outbreak of diseases has rapidly shifted to significant concerns regarding the safety of vaccines. Scientific evidence has time and again refuted a number of misconceptions pertaining to the safety of vaccines. However, parental refusal of application of vaccines in found to be increasing. The causal relationship between vaccines and autism is constantly under examination and novice methods are being considered for carrying out reliable studies in this regard. The association between receipt of measles–mumps–rubella vaccine and autism is widely debated within the medical domain. It is necessary that further research is carried out for finding the exact answer to the question of whether vaccine leads to autism. Such research needs to be done based on the findings of previously conducted studies in the same direction. Aligning the research with the already generated information would be advantageous. Government health bodies must become conscious and aware of the need of high-grade research. Funding and allocation of resources must be adequate so as to facilitate such research that potentially throw light on the extent to which vaccines are safe for use.

References

Ahmed, A., Sahota, A., Stephenson, I., Brown, K.E. and Tang, J.W., 2016. Measles–a tale of two sisters, vaccine failure, and the resurgence of an old foe. Journal of Infection.

Boutot, E.A., 2016. Autism spectrum disorders: Foundations, characteristics, and effective strategies. Pearson.

Brunsdon, V.E. and Happé, F., 2014. Exploring the ‘fractionation’of autism at the cognitive level. Autism, 18(1), pp.17-30.

Callaway, E., 2017. Medical research: The vaccine chronicles. Nature, 542(7640), pp.163-163.

Colaizzo, G.R., 2016. Misinformed parents, unvaccinated children and the fabricated vaccine-autism scare. Paediatrics and Health. 4 (1).

Daniels, A.M. and Mandell, D.S., 2014. Explaining differences in age at autism spectrum disorder diagnosis: A critical review. Autism, 18(5), pp.583-597.

Deisher, T.A., Doan, N.V., Omaiye, A., Koyama, K. and Bwabye, S., 2014. Impact of environmental factors on the prevalence of autistic disorder after 1979. Journal of Public Health and Epidemiology, 6(9), pp.271-286.

DeLong, G., 2011. A positive association found between autism prevalence and childhood vaccination uptake across the US population. Journal of Toxicology and Environmental Health, Part A, 74(14), pp.903-916.

Geier, D.A., King, P.G., Sykes, L.K. and Geier, M.R., 2008. A comprehensive review of mercury provoked autism. Indian Journal of Medical Research, 128(4), p.383.

Goin-Kochel, R.P., Mire, S.S., Dempsey, A.G., Fein, R.H., Guffey, D., Minard, C.G., Cunningham, R.M., Sahni, L.C. and Boom, J.A., 2016. Parental report of vaccine receipt in children with autism spectrum disorder: Do rates differ by pattern of ASD onset?. Vaccine, 34(11), pp.1335-1342.

Healer, J. and Cowman, A.F., 2016. Vaccine Development. In Molecular Parasitology (pp. 509-525). Springer Vienna.

Jain, A., Marshall, J., Buikema, A., Bancroft, T., Kelly, J.P. and Newschaffer, C.J., 2015. Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. Jama, 313(15), pp.1534-1540.

MacDonald, N.E., 2015. Vaccine hesitancy: Definition, scope and determinants. Vaccine, 33(34), pp.4161-4164.

Novella, S., 2016. Autism-Vaccine Link Researcher Andrew Wakefield Accused of Faking His Data. Skeptical Inquirer.

Taylor, L.E., Swerdfeger, A.L. and Eslick, G.D., 2014. Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies. Vaccine, 32(29), pp.3623-3629.

Uno, Y., Uchiyama, T., Kurosawa, M., Aleksic, B. and Ozaki, N., 2015. Early exposure to the combined measles–mumps–rubella vaccine and thimerosal-containing vaccines and risk of autism spectrum disorder. Vaccine, 33(21), pp.2511-2516.

Wexler, D.L. and Coalition, I.A., 2016. The Vaccine Handbook: A Practical Guide for Clinicians.