Dismantling common arguments against vaccination
Irene Jurado
Early Stage Researcher 1, University College Dublin
May 2020
Vaccines are among the greatest achievements of modern times and have brought several benefits to human public health (read more here). Nonetheless, over the past few years, vaccine hesitancy has gathered strength, driving down vaccine coverage and leading to outbreaks (14). Moreover, in 2019, the WHO listed vaccine hesitancy as one of our top ten global health threats (2). The reasons for vaccine refusal are complex and differ depending on the geographical and cultural context (14), but they are strongly fueled by misinformation easily propagated through the Internet by the anti-vaccine movement (7,8). We will describe the most frequent arguments used by this community (6,7) and scientifically explain why they are incorrect.
Common argument 1: “Vaccines are toxic because they contain dangerous chemicals, such as antifreeze, mercury, formaldehyde or aluminium”
These molecules are essential to keep the vaccine safe and prevent degradation. It should be noted that the safety of every element used in vaccines is carefully checked before (and after) licensure (16). But they are present in vaccines in quantities that are not harmful based on exposure studies in humans and experimental studies in animals (12). Moreover, many occur naturally in our bodies, e.g. the levels of these additives are equivalent to the levels in pears and bananas (9) and we absorb higher levels of aluminium from the air, food (even breastfeeding), and cosmetic products (12). Also, formaldehyde is naturally present in our body because it is an essential intermediate in the synthesis of the protein in our cells (12). The mercury-based compound used in vaccines (thimerosal) contains ethylmercury, which, unlike methylmercury, is not toxic (3). Nevertheless, and despite the lack of harmful evidence, this element has been removed from most vaccinations since 2001 (11). What is more, our body eliminates these compounds from tissues through various excretion systems (3,5). By contrast, other elements such as “antifreeze” have never been present in vaccines (15).
Common argument 2: “The schedule has too many vaccines and can overwhelm a child’s immune system because it is too immature to handle them”
First of all, from the moment we are born, we are naturally exposed to thousands of microbes, so the relatively few additional antigens introduced via vaccination are negligible (13). Secondly, a child’s immune system can respond to vast numbers of antigens (109-1010), even at the same time (13). Moreover, while the number of vaccines has increased, the number of antigens in vaccines has decreased (3,13). Finally, biological evidence and data obtained from over four large studies refute the concept that vaccines weaken the immune response (3,13).
Common argument 3: “Most vaccine-preventable diseases are harmless, and naturally obtained immunity is better”
The concepts of “natural” is often linked to “good” and “unnatural” to “bad”. Despite this being inherently wrong (there are toxic elements in nature), this “logic” overlooks the higher risks natural infections possess. Many vaccine preventable diseases cause severe complications when compared to the risk associated with any vaccine and can be fatal (16). Additionally, not all naturally occurring infections can generate long-lasting and robust immunity, and some vaccines (e.g., tetanus and influenza) actually provide more effective immunity (10). Last but not least, vaccines are not unnatural since they stimulate our immune system to produce its own protection, just like a natural infection would, but without having to get sick first to develop immunity (16).
Common argument 4: “Vaccines cause autism, allergies, and other mental or autoimmune disorders”
The publication of an article in 1998 that linked autism with the measles, mumps, rubella vaccine (MMR) triggered this belief. However, it was immediately retracted by the journal because clinical and biological data was misrepresented, and the study was not well designed, meaning that the proposed link was untrue. Additionally, and despite lacking a plausible biological explanation, several large studies that disproved this link have been performed (3,4). Similarly, several studies have proved that there is no correlation between vaccines and multiple sclerosis, allergies, neurotoxicity, or other diseases (3).
Common argument 5: “Vaccines have life-threatening secondary effects”
It must be noted that nothing can ever be 100% safe, and a balance should be sought between the risk of a side effect and the risk of the disease: benefits of vaccination greatly outweigh the slight risk they could have (1,3,6). Furthermore, both pre- and post-licensure studies have shown that severe adverse events after vaccination rarely occur (3), and when so, it is usually due to a scheduling error not related to vaccine manufacture (1). Usually, vaccines only provoke minor, transient effects (1).
Common argument 6: “Before vaccines were introduced, diseases were already declining due to hygiene and sanitation”
Although they have had an irrefutable impact on disease, there is considerable evidence of vaccines being the direct cause for their decline (1). The permanent decline in measles incidence occurred only after the approval and wide use of the measles vaccine, and this pattern has also been observed for other vaccine-preventable diseases (1). Besides, when immunization levels dropped in several developed countries, the annual incidence of and deaths due to these vaccine-preventable diseases such as measles drastically raised (while hygiene and sanitation remained the same) (1).
References
1. World Health Organization (WHO): Six common misconceptions about immunization. 2020. [https://www.who.int/vaccine_safety/initiative/detection/immunization_misconceptions/en/index1.html]. Acessed: 13/05/2020.
2. World Health Organization (WHO): Ten threats to global health in 2019. 2019. [https://www.who.int/news-room/feature-stories/ten-threats-to-global-health-in-2019]. Acessed: 13/05/2020.
3. Geoghegan, S., et al. “Vaccine safety: myths and misinformation”. Front. Microbiol., 2020. 11p372.
4. Gerber, J.S., et al. “Vaccines and autism: a tale of shifting hypotheses”. Clin. Infect. Dis., 2009. 48(4)pp456-461.
5. Goullé, J.P., et al. “Aluminum and vaccines: Current state of knowledge”. Med. Mal. Infect., 2020. 50(1)pp16-21.
6. Kata, A. “Anti-vaccine activists, Web 2.0, and the postmodern paradigm-an overview of tactics and tropes used online by the anti-vaccination movement”. Vaccine, 2012. 30(25): 3778-3789.
7. Kata, A. “A postmodern Pandora's box: anti-vaccination misinformation on the Internet”. Vaccine, 2010. 28(7): 1709-1716.
8. Kennedy, J. “Vaccine hesitancy: A growing concern”. Paediatr. Drugs, 2020. 22(2): 105-111.
9. Kluger, J. “How a vaccine is like a banana — and why that's good”. Time, 2015.
10. Marshall, G.S. "Addressing concerns about vaccines". The Vaccine Handbook: A Practical Guide for Clinicians, 2010. p209.
11. Offit, P.A. “Thimerosal and vaccines--a cautionary tale”. N. Engl. J. Med., 2007. 357(13): 1278-1279.
12. Offit, P.A., et al. “Addressing parents' concerns: do vaccines contain harmful preservatives, adjuvants, additives, or residuals?”. Pediatrics, 2003. 112(6 Pt 1): 1394-1397.
13. Offit, P.A., et al. “Addressing parents' concerns: Do multiple vaccines overwhelm or weaken the infant's immune system?”. Pediatrics, 2002. 109(1): 124-129.
14. Salmon, D.A., et al. “Vaccine hesitancy: causes, consequences, and a call to action”. Am. J. Prev. Med., 2015. 49(6 Suppl 4): S391-8.
15. Smith, T.C. “Vaccine rejection and hesitancy: A review and call to action”. Open Forum. Infect. Dis., 2017. 4(3): 146.
16. Vetter, V., et al. “Understanding modern-day vaccines: what you need to know”. Ann.Med., 2018. 50(2): 110-120.
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