Vaccinations and autism: is there a link?

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Vaccinations and autism: is there a link?
Vaccinations and autism: is there a link?
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More than 20 years ago, a study was published in the Lancet that argued that there was a direct link between vaccinations and autism. Parents sounded the alarm, an anti-vaccine movement appeared. Over time, the results of that work were refuted, but the number of opponents of vaccinations is growing. Naked Science tried to understand the reasons for the growing anti-vaccine community and the link between vaccines and autism.

Vaccinations and autism: is there a link?

Why are people so confident about the link between vaccines and autism?

The anti-vaccine people are a small but vocal group who disagree with the general scientific view that vaccines are safe and do not lead to autism. Most of the people in this camp do not care that more than ten studies have stalled in the search for the alleged connection between the two phenomena. How can this be? How can people deny scientific evidence? It's all about the so-called Dunning-Kruger effect - a cognitive bias that explains anti-vaccine moods.

The Dunning-Kruger effect, proposed by David Dunning and Justin Kruger in 1999, describes a situation in which people with very little information on a topic are confident that they know significantly more specialists. One of the founders of the concept of this effect, David Dunning, explained it this way: "The area of ​​people's ignorance is often invisible to them."

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In 2018, a team of researchers led by Dr. Matt Mott of the University of Pennsylvania's Annenberg Center for Public Policy conducted a survey and found that people who knew little about autism, lacked basic knowledge, and were inclined to believe disinformation believed they knew more experts. This overconfidence leads to the fact that some do not support the policy of compulsory vaccination and show skepticism towards doctors.

1,310 people took part in the survey. Dr. Mott's team found that 36% of those surveyed believed they knew more doctors, and 34% said they were aware of the possible causes of autism. The highest degree of self-confidence was observed among those with the lowest level of knowledge and the highest tendencies towards maintaining disinformation. These same people showed a predisposition to keeping non-specialists - like various celebrities - involved in policy making.

Many people think that anti-vaccine moods are not dangerous, but scientific studies like the one described above show that they affect the real world. Thus, communities opposed to vaccination are steadily multiplying. And it is not surprising that they are the ones who are at the greatest risk of contracting viruses from which they refuse to be vaccinated. It is even worth remembering the measles outbreak in late 2018 and early 2019.

In 2018, Dr. Peter Hotez of the National School of Tropical Medicine at Baylor College of Medicine conducted a study that found an increase in non-medical exemptions from vaccinations in 12 of 18 states that allowed the practice.

“In recent years, there has been a growing social anti-vaccination movement in the United States; as a result, measles outbreaks have become more frequent,”Hotez and his colleagues said at the time.

Back in mid-2018, Hotez's research team noted that increased resistance to vaccination would also be followed by more outbreaks.

Nevertheless, the anti-vaccine communities continue to grow and repeat like a mantra or incantation that vaccines provoke the development of autism.

2015 study and getting off the ground

In 2015, the Journal of the American Medical Association published an article about a large-scale study at that time, the purpose of which was to confirm or deny the connection of the MMR vaccine (combined vaccine against measles, mumps and rubella) with the occurrence of autism (the study report itself can be found link.

The work, conducted by Dr. Anjali Jain and her colleagues, looked at the medical histories of 95 thousand children, among whom were 15 thousand unvaccinated between the ages of two and five, as well as about two thousand children already at high risk of developing autism.

As with previous similar studies, researchers found no link between the MMR vaccine and the risk of developing autism spectrum disorder (ASD). This has proven to apply to nearly two thousand children at high risk of developing autism.

“Consistent with a study of other populations, we did not observe an association between the MMR vaccine and an increased risk of ASD,” the authors wrote. "We also found no indication that receiving one or two doses of MMR vaccine was associated with an increased risk of ASD among children who have older siblings with ASD."

The analysis looked at rates of autism and MMR vaccine among children aged two to five years. The researchers did not identify an increased risk of developing autism in connection with immunization at any of the indicated ages. Moreover, there were fewer cases of autism among the vaccinated groups. But, as the scientists noted, this may be due to the fact that parents, noticing early signs of autism, could postpone vaccination or refuse it altogether.

It is important to note that there have been studies over the years that have attempted to identify a causal relationship between the MMR vaccine and autism. Each time, the samples increased, but no connection was established. In 1998, the Lancet published a study by Dr.Andrew Wakefield and colleagues, which argued the opposite: there is a direct link between vaccinations and autism.

To date, this study has been refuted and withdrawn from the journal. If you follow the link, then on the background of the text you can see a large inscription in red letters: "RETRACTED". It is not surprising that such a high-profile article aroused interest among other specialists, and they, in turn, decided to conduct their own research. As already mentioned, no confirmation of the described data could be found. However, the speculation that surrounds this issue to this day gives many people anxiety. Many become "victims" of the Dunning-Kruger effect. It can also be assumed that it was these unrest that caused the decline in the number of vaccinations among families in which the older child suffers from autism - at least this is what the authors of the 2015 study suggest. In the wake of Dr. Wakefield's article, many other articles were withdrawn that talked about the discovery of a link between vaccinations and autism.

Be that as it may, in 2015, Dr. Jain's work showed that among families without children with autism, 84% of children aged two years and 92% of children under five years old were vaccinated. In families with the oldest child with autism, vaccination rates were significantly lower: 73% of children aged 2 years and 86% of children under 5 years of age.

Danish survey 2018 - a new frontier

In the United States, measles was eliminated in 2000. In 2010, the World Health Organization approved a strategy for the global elimination of measles by 2015.It was ambitious and seemed quite feasible.

By early 2019, there were 206 measles cases in 11 states in the United States. In the EU, 82,596 measles cases were reported from January to December 2018. The return of the disease is directly related to parents, who increasingly refused to vaccinate their children with MMR vaccine. This certainly does not play into the hands of parents who vaccinated their children in an attempt to protect them from infectious diseases such as measles, rubella and mumps. The anti-vaccine movement as a whole is based on Dr. Wakefield's research already mentioned above. It was he who first linked vaccination with the increasing number of cases of autism in children. Despite the fact that his research was disproved by 2010, the widespread belief in Wakefield's claims proved incredibly resilient.

The most recent study on the subject was published in the Annals of Internal Medicine on March 5 this year. It is based on data collected over ten years from half a million people. However, we note that, despite an unprecedentedly large sample, anti-vaccine users, guided mostly by paranoia, shifting blame on others, mistrust of specialists, and even simple stubbornness, are unlikely to consider this significant evidence to refute beliefs.

The study was conducted by scientists from the Statens Serum Institute in Denmark. In the course of it, no statistical link was found between receiving a vaccine and the possible development of autism (the work is available here. Also, there was no connection between the areas in which vaccines are used and those associated with the development of autism. Moreover, with the growth of the anti-vaccine community The incidence of autism has also increased, with one out of 68 children having autism in 2016, and in one out of 59 in 2018.

The researchers examined the medical records of Danish children born between 1999 and 2010. Using a population register, the researchers assessed other risk factors, including cases of autism among siblings, as in a 2015 study, and thoroughly investigated the alleged relationship between vaccinations and the development of autism. Discussing the statistics presented in the study, health expert Saad Omer said in an interview with the Washington Post, "The correct interpretation is that there is no connection at all."

However, the same Omer and a number of other experts believe that, despite all the evidence presented in the Danish study, the waste of research funds on persuading anti-vaccinators is a dubious undertaking. Bioethicist Sid M. Johnson commented: "They are immune to facts." Almost concurrently with the study, Omer published an editorial in the Annals of Internal Medicine decrying the waste of time, effort, and money in people living in a "fact-resistant" world.

Omer and others are concerned that anti-vaccine beliefs undermine public confidence in vaccines, and believe that the financial cost of gathering evidence to the contrary is justified only if the cost of such research is not prohibitive. He also noted that this money can be spent in an alternative way, namely, on the development of drugs.

The publication of this study coincided almost perfectly with a US Senate hearing in which 18-year-old Ethan Lindenberger testified about his decision to get vaccinated against his parents' wishes. Lindenberger previously wrote on Reddit that after reading the posts on Facebook, his mother was convinced that vaccines were "some kind of government scheme." In his post, he writes: “In a few weeks, I have an appointment for injections! My mom was very angry, but my dad said that since I'm 18, he doesn't really care.Despite the fact that my mom tries to convince me not to do this and says that I do not care about her, I know that I just need to do it, no matter what."

In turn, Facebook said it is taking the necessary steps to limit the spread of health-related misinformation. Already on March 6, the company announced a new plan to block all advertisements containing false information about vaccines, and eventually block ad accounts for pages that continue to violate network rules.

Situation for today

The desire of anti-vaccine parents to control their children's health decisions is logical, but unfortunately for them, their children - and other children with whom they may come into contact - are not immune to infectious diseases.

As a result, all other people have no choice but to sit and watch the possible return of serious illnesses. So, today many states in the US allow "religious" waiver, allowing parents to refuse to vaccinate their children, but, as statistics indicate, this problem is not only in the United States. Due to the increasing number of measles cases, WHO ranks “vaccination uncertainty” as one of the ten most serious threats to global health in 2019, which could lead to 1.5 million deaths annually.

In the article by Dr. Omer, already mentioned, he, as a public health researcher at Emory University, and Dr. Inchi Yildirim of Emory School of Medicine, note: despite the fact that since the publication of a small study that has provoked mass hysteria about the alleged link between vaccines and autism After enough time, researchers continue to use resources for research aimed at refuting that work.

"In an ideal world, vaccine safety research would only be conducted to assess evidence-based hypotheses, not in response to a conspiracy," they write in their article.

In the same material, scientists argue that doctors and other public health officials should firmly call this connection a "myth."

The representative of the American Academy of Pediatrics, Associate Professor of the Department of Pediatrics at the University of Colorado at Denver, Dr. Sean O'Leary, also spoke on the same topic. He noted that refuting a myth can be difficult and that every time someone repeats it, there is a risk of reinforcing it.

“All parents will remember from your complicated explanation about why vaccines do not cause autism is that they are somehow related,” says O'Leary. “Therefore, pediatricians should focus on the diseases that we are trying to prevent, and if a myth needs to be mentioned, it should be noted that it is exactly what it is.”

Dr. O'Leary also noted that doctors who work with parents need to have factual and accurate information for those who want to take a deeper look at this issue, since due to the background information noise in the media and, in particular, social networks, modern parents can it can be difficult to distinguish truth from fiction.

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