Debunking Denialism

Irrefutable Evidence Shows That Anti-Vaccine Activists Still Have No Clue

Intellihub is an online “alternative” news site that claims to provide “independent news for independent minds” founded by Shepard Ambellas. The background story is already cliché: mainstream media are somehow controlled by evil corporations and Intellihub wants to “inform” people what is really going on by providing them “top notch information”. In reality, the so called news site is a propaganda tool used by conspiracy theorists to spread their pseudoscientific falsehoods about 9/11, synthetic biology, genetically modified foods, alleged depopulation and vaccines.

In a recent anti-vaccine post, Dave Mihalovic spews the same old recycled garbage that defenders of science-based medicine has refuted thousands of times. In stark contrast to the claims made by Mihalovic, vaccines led to a decline in the spread of infectious diseases, vaccines provide only a negligible challenge to the immune system of the developing child, the increase in allergies can be explained by the hygiene hypothesis and correlation between two things does not imply a causal relationship.

Vaccines effectively combats vaccine-preventable diseases

Vaccines successfully reduce the occurrence of new infections. It is true that better hygiene and cleaner water also helped in preventing the spread of vaccine-preventable diseases, but it was not until the widespread use of vaccines that the incidence of new infections drastically dropped. Let us take diphtheria as an example. Here is how the CDC Pink Book describes the diphtheria situation before vaccines:

In the 1920s in the United States, 100,000–200,000 cases of diphtheria (140–150 cases per 100,000 population) and 13,000–15,000 deaths were reported each year. In 1921, a total of 206,000 cases and 15,520 deaths were reported. The number of cases gradually declined to about 19,000 cases in 1945 (15 per 100,000 population). A more rapid decrease began with the widespread use of toxoid in the late 1940s.

So while there was a decline in the number of new cases, it was not until the vaccine (using an inactivated form of the toxin called a toxoid) was used that the decrease became more rapid. Here is the graph:

A similar story can be found for other vaccine-preventable diseases such as measles, polio, pertussis, Hib and many others.

Anti-vaccine advocates cannot argue against these hard facts, so they try to distract you with an irrelevant smokescreen by claiming that the mortality rate for these disease went down before the vaccines were used. For instance, when the iron lung was used to combat paralytic polio, people who would otherwise suffocate to death could live and so the death rate went down. However, this argument misunderstands the nature of vaccines. Vaccines aim to reduce the spread of infectious diseases, not reduce the mortality rate once you have been infected.

Another classic anti-vaccine trope is to assert that this argument makes the post hoc fallacy. However, it is not merely that the disease incidence dropped after vaccination, but that vaccination has a well-tested mechanism from causing this drop in incidence. This mechanism is reducing the average number of new cases that an infected individual give rise to. As this drops below 1, the spread is decreased.

Vaccines offer a negligible challenge to the immune system of developing children

A single bacterium can produce a couple of thousand different challenges (called antigens) to the immune system. A young infant is covered by literally billions of bacteria, both on the skin and in the intestine. The number of immunological challenges from all vaccines given today combined is less than 200. In the past, this figure was even bigger (owing to e. g. whole-cell vaccines) but with the advent of genetic engineering, this figure has dropped (as we can remove the unnecessary components).

Anti-vaccine cranks often claim that vaccines overwhelms the infants immune system or that they are given too many too son. However, the immune system of an infant is challenged by thousands of antigens from normal bacteria every day with little problem and the challenge from vaccines is negligible in comparison (Gerber and Offit, 2009; Offit et. al. 2002)

Smallpox was eradicated by global vaccination

Although the vaccination campaign against smallpox in the late 19th century and early 20th century had limitations (e. g. public resistance, ineffective laws, ineffective vaccination procedures, no access to modern vaccine technology or safety testing), smallpox was finally vanquished and eradicated by vaccination in the 1970s.

Mihalovic tries to dismiss this huge achievement by modern medicine by pointing out limitations with the vaccination campaigns in the late 1800s and early 1900s. This is misguided because it has little relevance to the vaccination campaign that eradicated smallpox in the 70s. In other words, Mihalovic is comparing apples and oranges.

Allergies and the hygiene hypothesis

The hygiene hypothesis states that exposure to immunological challenges is necessary for the optimal development of the immune system. This is because it promotes the development of regulatory T cells that suppress unwanted immune responses, such as allergies. So if a child is raised in an ultra clean environment and thus not exposed to garden variety microorganisms, fewer regulatory T cells will develop and the risk of e. g. allergies is increased.

Vaccines prevent only a limited number of diseases (around 15 or so) and not some of the most common pathogens that an infant is exposed to regularly. It is therefore implausible that vaccination contributes to allergies. Studies reviewed in Offit and Moser (2011) has shown that vaccines do not increase the risk of developing allergies.

Correlation does not entail causation

The number of pirates have declined as the global average temperature has increased. Further, the increase in consumption of coca-cola correlates with the increase in antibiotic resistant bacteria. Does this mean that we need more pirates to stop global warming or that coca-cola cause antibiotic resistance to evolve? No, because a correlation between two things does not by itself entail that one of them caused the other.

Mihalovic makes a long list of these kinds of correlation fallacies, trying to link vaccines to asthma, allergies, ADHD and others. However, this confuses correlation with causation and there is no reason to take them seriously unless hard evidence is presented (which Mihalovic does not).

Conclusion

The spread of vaccine-preventable diseases fell drastically because of the vaccine after it was introduced. Vaccines offer negligible challenges to the infant immune system, far less than normal bacteria that the child is exposed to every day without much problem. Smallpox eradication is a huge success in modern medicine. The hygiene hypothesis explains the increase in prevalence of allergies and correlating the increased awareness for a condition with vaccines is a correlation fallacy.

References

Gerber, J. S., & Offit, P. A. (2009). Vaccines and Autism: A Tale of Shifting Hypotheses. Clinical Infectious Diseases, 48(4), 456-461.

Offit, P. A. & Moser, C. A., (2011). Vaccines and Your Child: Separating Fact from Fiction. New York. Colombia University Press.

Offit, P. A., Quarles, J., Gerber, M. A., Hackett, C. J., Marcuse, E. K., Kollman, T. R., . . . Landry, S. (2002). Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System? Pediatrics, 109(1), 124-129.