Meta-analysis And Systematic Review Of Studies On Vaccination And Autism

No relation between vaccination and autism

Additional search strategy can include the keywords “vaccination and autism”; AUTISM and MMR Vaccination” and “risks of MMR Vaccination”.

Table 3: Experimental quantitative studies

Table 4: Qualitative study

The studies above provide significant information regarding the concerns about immunization safety and the assumed relation between vaccination and autism. Several studies refuted the links between vaccinations (with MMR) with autism spectrum disorders. Taylor et al., (2014) pointed out that there was no significant relation between vaccination and autism, and neither are any of the components of MMR, thimerosal or mercury doses are linked to the incidence of Autism Spectrum Disorder. This can be a significant knowledge for the parents, as it can help to refute the notion about the possibility of autism being caused due to these vaccinations.

Studies by Jefferson et al., (2003), also supported the same findings, that autism and vaccination were not related. Their studies also found no relation between vaccination and Crohn’s disease, thereby refuting the notion of autism or any other mental health condition being created due to vaccination. However, the study did show certain risks for irritable syndrome and benign thrombocytopenic purpura (TP). Such an aspect is very crucial, as it can help the parent to understand the possible adverse effects of the vaccination and being able to differentiate real risks from the perceived ones.

Guillaume and Bath (2004) studied the vaccine scare of the parents of children, due to which they were reluctant to immunize their children. The study showed a lack of trust on traditional and government based sources of information, due to which it was difficult to believe the information provided by them. The media firestorm that initiated due to the publication by Andrew Wakefeild in 1998 that showed the incidence of autism in 8 patients after being administered MMR vaccination as the main contributor of the fear of vaccination (Offit, 2015). Even though the original paper was retracted by Lancet (the publisher), the widespread fear still exists among the parents.  Studies by Jain et al., (2015) also provided a compelling evidence by studying the incidence of autism due to vaccination among children with older siblings already diagnosed with autism (thereby placing the selected children in a high risk group for autism spectrum disorders) and found no correlation between vaccination and the risk of developing autism. Furthermore, mercury exposure due to preservative thimerosal does not have a causal relationship with autism in children (Schultz, 2010). Any relation between thimerosal and autism were refuted by other studies as well (Nelson & Bauman, 2003). Even the number and timing of the vaccination did not show any correlation with the development of Autism. Due to the initial scare caused by the studies that incorrectly hypothesized a relation between vaccination and autism, it was harder to convince them, as it lead to them developing a critical mindset about the validity of traditional sources of information (Offit, 2015). Moreover, Immunize.org lists more than 25 peer reviewed articles, all of which refutes the connection between MMR vaccination and Autism.

Refutation of links between vaccinations with autism spectrum disorders

Such findings can help to raise the awareness of the parents about the most relevant findings on this topic and also help to develop trust on the source of information. The parents can be made aware of the various studies that found no relation between vaccination and autism, even among children considered at high risk. Moreover, it is important to clarify the initial mistake that lead to the incorrect assumption of vaccine to be causally related to autism. It is also important that the fears of the parents be properly addressed regarding vaccination. An effective strategy to convince the parents to vaccinate their children with MMR is to make them understand the burden of diseases like Measles, which can be prevented with MMR vaccination. Mindset of individuals about vaccination can also be changed by displaying pictures that portray the adverse health complications related to these diseases (Nyhan et al., 2014; Sciencemag.org, 2018). It is also important that the physicians are able to identify parents who have decieded not to vaccinate their children and those who are undecisive about it. It can be inferred that convincing the undecisive parents might be easier than undecisive parents (Sciencemag.org, 2018).

Several parents additionally had negative views on the pharmaceutical industry due to which their trust on vaccines are limited. Lewandowsky et al., (2013) also proposed that a free market ideology is a strong predictor of antivaccine sentiments, and many people oppose vaccination on the grounds that it infringes upon the rights of the patient. A shockingly high correlation exists between vaccine rejection and conspiratorial thinking. All of which further reduces their trust on the healthcare systems (Sciencemag.org, 2018).

During the discussion with parents or pregnant women regarding the vaccination of the children, the following aspects can be focused on:

• Informing about the adverse effects of measles, mumps and rubella
• Explaining what autism is and how it is caused
• Informing the parents of various studies that refutes relation between vaccination and autism
• Explaining how the initial fear for vaccination was raised and how it was incorrectly assumed
• Supporting evidences from the relevant authors
• Reducing the vaccine fear of the parents
• Improving their trust on traditional sources by citing other examples of reliability of their information
• Helping the parents to differentiate between a reliable and non reliable source. 

References:

DeStefano, F., Price, C. S., & Weintraub, E. S. (2014). Increasing Exposure to Antibody-Stimulating Proteins and Polysaccharides in Vaccines Is Not Associated with Risk of Autism. Pediatria Polska, 89(5), T31-T38.Immunize.org (2018). MMR Vaccine Does Not Cause Autism Examine the evidence!. [online] Immunize.org. Available at: https://www.immunize.org/catg.d/p4026.pdf [Accessed 27 Mar. 2018]

Guillaume, L. R., & Bath, P. A. (2004). The impact of health scares on parents’ information needs and preferred information sources: a case study of the MMR vaccine scare. Health Informatics Journal, 10(1), 5-22.

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

Jefferson, T., Price, D., Demicheli, V., Bianco, E., & European Research Program for Improved Vaccine Safety Surveillance (EUSAFEVAC) Project. (2003). Unintended events following immunization with MMR: a systematic review. Vaccine, 21(25-26), 3954-3960.

Lewandowsky, S., Gignac, G. E., & Oberauer, K. (2013). The role of conspiracist ideation and worldviews in predicting rejection of science. PloS one, 8(10), e75637.

Nelson, K. B., & Bauman, M. L. (2003). Thimerosal and autism?. Pediatrics, 111(3), 674-679.

Nyhan, B., Reifler, J., Richey, S., & Freed, G. L. (2014). Effective messages in vaccine promotion: a randomized trial. Pediatrics, 133(4), e835-e842.

Offit, P. A. (2015). Vaccines and autism in primate model. Proceedings of the National Academy of Sciences, 112(40), 12236-12237.

Prymula, R., Bergsaker, M. R., Esposito, S., Gothefors, L., Man, S., Snegova, N., … & Vassilev, V. (2014). Protection against varicella with two doses of combined measles-mumps-rubella-varicella vaccine versus one dose of monovalent varicella vaccine: a multicentre, observer-blind, randomised, controlled trial. The Lancet, 383(9925), 1313-1324.

Sciencemag.org (2018). Can skeptical parents be persuaded to vaccinate?. [online] Science | AAAS. Available at: https://www.sciencemag.org/news/2017/04/can-skeptical-parents-be-persuaded-vaccinate [Accessed 27 Mar. 2018].

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