Vaccine Hesitancy: Placing Everyone at Risk
by Alister R. Olson, Michael P. Clough, and Benjamin C. Herman
This story highlights four tactics of science misinformation and disinformation efforts: the lack of competence among false experts, creation of false legitimacy in order to fabricate a fake scientific controversy, putting forth conspiracy theories, and appeals directly to the public. See Features of Science Misinformation/Disinformation Efforts: Understand how to detect false information for more information regarding these tactics.
We never know the love of a parent till we become parents ourselves.
-Henry Ward Beecher
Regardless of era, society, politics, or culture, the love of parents for their children is constant. Parents worry about the safety and happiness of their children, and agonize over whether they are making the best choices for them. With greater availability of information on the internet, and the traditional patient-doctor dynamic shifting from a one-way paternalistic relationship to a shared responsibility between parties  , parents are increasingly involved with medical decisions related to their children—including whether or not to vaccinate them.
No one wants to hurt their kids
Linda and Ian Williams are an example of loving parents of three children. In December of 2012, their seven-year-old boy, Alijah, received a cut on his foot. The wound was small, so the New Zealand couple thought little of the injury. However, two days later, Alijah began experiencing disconcerting symptoms: his face was cramping, and he was in severe pain . After being admitted to the hospital, the boy’s muscle contractions became so severe that his heart was at risk of stopping, and his bones were under such immense strain that they could break at any moment. Ian recalled that, “Blood is dripping from his mouth and he is saying ‘save me daddy’ .” Eventually, Alijah had to be placed in a medically-induced coma to alleviate his pain  . Within the sedated boy’s body, toxins that had been produced by the bacterium Clostridium tetani were ravaging his nerves—an infection commonly known as tetanus.
Tetanus has no known cure, and its effects can be fatal . Fortunately, tetanus is now a rare disease in many countries, such as the United States, where deaths from the infection have decreased by over 99% since 1947 . The decrease in cases and deaths is attributed to the tetanus vaccine—a preventative shot which Alijah had not received. Ian and Linda are intelligent people who clearly love their children. In fact, Ian even has a science degree, and he had researched the pros and cons of vaccinations on the internet before choosing against the vaccines. What could cause a significant number of parents, such as the Williamses, to conclude that their children should not receive vaccinations?
Hesitancy and the first vaccine
Smallpox was one of the most devastating diseases in human history. Nearly 30% of people who contracted the virus died, and survivors were often left blind and/or with permanent scars from the pustules that cover the body during infection (Figure 1) . By the end of the 18th century, the virus killed an estimated 400,000 people per year in Europe alone . While germ theory would not be widely accepted until the late 19th century, people still found ways to combat the virus hundreds of years earlier. Most notably, people in areas of Asia and Africa developed a variety of iterations of variolation, that involved infecting healthy people with infected material (e.g., liquid from a smallpox pustule). The hope was that a mild infection would occur that would then result in protection against the disease. While variolation did generally produce milder symptoms than natural smallpox, deaths did still occur, and people who had been variolated could spread the disease .
The British physician Dr. Edward Jenner, who had nearly died at age 8 after undergoing variolation, would eventually provide a more effective and safer alternative. In 1770, Jenner had heard from a dairymaid that cowpox, a disease sharing similarities with smallpox but with considerably milder consequences, could protect against smallpox. The idea was not novel among farm workers, but the Medical Society of London had refused to publish about the topic, and many physicians considered the idea to be a myth. Jenner, who was undeterred by the highly skeptical, and at times even hostile reaction of the medical community, began to carefully study the potential protection against smallpox conveyed by cowpox exposure. In 1789, he began a series of trials, taking liquid from the pustules of individuals infected with cowpox, and using it to inoculate numerous people, including his own children. By 1800, Jenner had published several books based on his studies. He was convinced of the lasting protection against smallpox that cowpox exposure provided, and that his vaccination procedure was superior to variolation .
Surprisingly, Jenner’s work was initially ignored by most of his colleagues . However, once the success of the treatment began to become apparent, apathy was quickly replaced by anger and attacks by some individuals. Physicians such as Dr. William Rowley and Dr. Benjamin Moseley, who both made substantial money from variolation, began to circulate drawings to members of the public that showed people supposedly transforming into animals as a result of Jenner’s vaccines (Figure 2) .
Figure 1. A young child from Somalia in the 1970s whose body is covered by smallpox pustules . image source
Figure 2. An illustration used to sow distrust of Jenner’s vaccine by depicting various forms of transformation into animals supposedly occurring after receiving it.
Another unfounded rumor created during that time accused cowpox of actually being syphilis, and that smallpox vaccinations were therefore transmitting the disease . Despite the aforementioned resistance and attacks, the success of Jenner’s vaccination techniques became apparent to many, as he received honors, awards, and letters of thanks from leaders around the world, including Napoleon, Thomas Jefferson, and King George IV . By 1840, variolation had been made illegal in England and Wales, and thirteen years later, the smallpox vaccine became required there by law . However, even Jenner’s success could not fully eradicate the public’s mistrust that Rowley and Moseley had helped to create. Concerns about contracting syphilis from the smallpox vaccine were still so prominent in 1897—74 years after Jenner’s death—that the Royal Commission on Vaccination felt compelled to release a report to the public that stated that there was no evidence linking syphilis to smallpox vaccinations. Despite the study, fear of the vaccine still remained .
Red Flag | Fabrication of a fake science controversy
Skepticism is an important element of science. Such a reaction was particularly appropriate in Jenner’s case, since he could not explain why his vaccine worked. However, note how some doctors inappropriately accused the vaccine of transforming people and causing syphilis when faced with the empirical success of Jenner’s work. Fabricating controversies that are not based on sound science and do not reflect actual debates within the scientific community is a warning sign of potential misinformation/disinformation.
By the 1950s, approximately fifty million cases a year of smallpox were still being reported globally. However, through an extraordinary global vaccination campaign, the World Health Organization declared in 1979 that smallpox had become the first disease to ever be completely eradicated by humans. The disease that had killed an estimated 300 million people in the 20th century alone was gone less than 200 years after Jenner developed his vaccine .
Note that science misinformation and disinformation efforts have a long history. What makes fabrication of a fake science controversy such an effective tactic of those sowing misinformation and disinformation?
In 1998, nineteen years after the eradication of smallpox, Dr. Andrew Wakefield published a bombshell article in the medical journal The Lancet. According to the article, the twelve children in the study had experienced normal development, but then lost language and acquired skills—changes that parents of eight of the participants had associated with the measles, mumps, and rubella (MMR) vaccine. Wakefield identified intestinal abnormalities in the twelve children, and discussed the MMR vaccine as a possible environmental trigger, although he did state that such an association had not been proven by his study [12, RETRACTED]. In an unusual move, Wakefield held a press conference prior to publication of his article. In that press conference, he asserted that the measles virus in the MMR vaccine was perhaps damaging the intestines, which could cause harmful proteins to enter the bloodstream and travel to the brain, resulting in autism . The posited MMR-autism link immediately drew significant public attention  . Many parents were understandably shaken by the news. Wakefield was a respected medical researcher at the prestigious Royal Free Hospital, and the The Lancet is one of the top medical journals in the world. Furthermore, other researchers soon expressed support for Wakefield’s link between the MMR vaccine and autism .
Red Flag | Appeals directly to the public
A strength of science is that it is not dogmatic, and new research is constantly changing how researchers understand the natural world. However, extraordinary claims in science require not only extraordinary evidence, but also the ability to withstand the scrutiny of the scientific community. That process requires time for data to be analyzed, debates to occur, and follow-up studies to be conducted. These steps protect the scientific community from wildly accepting every idea that is raised, and helps bolster confidence in the knowledge on which the community does reach consensus. For those reasons, many scientists were surprised to see Wakefield’s press conference occur before his article in The Lancet was even published. Such an appeal directly to the public prior to letting the broader scientific community provide feedback on the research is uncommon with legitimate scientific work, and it is often a warning sign of potential misinformation/ disinformation.
Next, Wakefield and others, including the Irish pathologist John O’Leary, attempted to identify measles virus in tissue samples taken from autistic children—findings that would support the hypothesized pathway between the MMR vaccine and autism. In a series of studies, PCR tests from O’Leary’s laboratory were used to supposedly identify the presence of measles virus RNA in the intestines and cerebrospinal fluid of a high percentage of children with developmental disorders, compared to control groups . However, other research groups conducting PCR studies of autistic children were coming to markedly different conclusions. Afzal et al. reported that “the data presented in this study failed to verify the finding of previous studies that predicted persistence of measles virus in autistic children with development regression .” Similar results were published by numerous other researchers, including Baird et al. , D’Souza et al. , and eventually even by O’Leary in a paper published with Hornig et al. .
Epidemiological studies, which often involve analysis of large data sets to test for the existence of significant relationships (e.g., dietary patterns and heart disease), were soon conducted to explore Wakefield’s conclusions. Taylor et al. looked at records of nearly 500 children in the United Kingdom with autism, and compared that to whether they had received the MMR vaccine, and if they had, when it was received . The authors reported no sudden increases in diagnoses of the children after receiving the vaccination, and concluded that their results did not support a causal link between the MMR vaccine and autism . By 2008, the epidemiological evidence against a link between the MMR vaccine and autism was significant. Over 20 such studies involving millions of children in numerous countries reported no link between the MMR vaccine and autism .
Nature of science connections
Note the similarities between the stories of Jenner and Wakefield: both were British medical doctors who brought forth ideas regarding vaccination that met significant opposition. However, Jenner's critics were reduced to fabricating and disseminating falsehoods about his work in the face of extensive supportive evidence. In Wakefield's case, the empirical evidence amassed against his proposed link, resulting in its eventual dismissal by the scientific community. Early scientific ideas that run counter to accepted knowledge of the time are often met with resistance by other scientists. Studies are conducted, and as the evidence supporting one side of the argument accumulates, scientists can generally be eventually won over. Over time, the scientific debate ends, because research coheres, consensus is reached on the issue, and the scientific community moves on. Those who refuse to give up the debate become increasingly isolated as their colleagues’ conversations shift to other topics. Media outlets often report novel science ideas before they are vetted by the scientific community. Consider why the public is in no position to judge such ideas until the legitimate community of science experts have accepted or rejected those claims.
Scrutiny of Wakefield’s research further undermined any connections that he had put forth. A Freedom of Information Act request revealed that Wakefield had been paid $800,000 by a personal injury lawyer in the United Kingdom to finance his original 1998 study. The lawyer, Richard Barr, was attempting to build a case against vaccine manufacturers, and in doing so he had distributed millions of dollars to other vocal supporters of Wakefield’s research in the medical community . Even more disturbing, an investigative reporter learned that Wakefield’s medical procedures on the children in his 1998 study—invasive procedures that had left one child with serious damage to his large intestine—had never been approved by the Ethical Practices Committee, despite a statement to the contrary in the paper . Also, at least five of the children involved in the study were litigants in the case being built against vaccine manufacturers. Finally, Deer noted that Wakefield’s study reported inaccurate diagnoses of autism for some of the children, inconsistencies regarding when behavioral symptoms first arose relative to receiving the MMR vaccine, altered histopathology reports, and inaccurate claims that all of the participants were “previously normal” when five in fact did have underlying developmental concerns . Wakefield’s follow-up studies were also problematic. John O’Leary’s laboratory that had used PCR to identify measles RNA in the intestines of autistic children, was not accredited, and it had received $1,000,000 from Richard Barr . An analysis of the PCR test results yielded numerous inconsistencies, including an impossible result that has been identified as likely stemming from DNA contamination of the laboratory. Dr. Stephen Bustin, who had investigated O’Leary’s laboratory, concluded that, “…I want to get the message out about the O’Leary-Wakefield research. There’s nothing in it.” Wakefield was asked to resign his position at the Royal Free Hospital in 2001 . In 2010, he was banned from practicing medicine in Britain due to ethics violations , and Wakefield’s original 1998 article in The Lancet article was officially retracted . Looking back on the supposed MMR-autism connection, DeStefano and Shimukuro wrote:
A meta-analysis of the published epidemiologic studies concluded that MMR vaccine is not associated with an increased risk of autism. The evidence for a possible association between MMR vaccine and autism also has been extensively reviewed by three committees of the National Academy of Medicine, and all have concluded that MMR vaccine does not cause autism. (p.592) 
Preservation of doubt
As scientists worked to investigate Wakefield’s MMR hypotheses, a series of events were about to take place that would lead to the rise of another vaccine-autism narrative. In 1999, Neil Halsey, a well-regarded pediatrician from Johns Hopkins Medical School, was serving as the head of the American Academy of Pediatrics’ (AAP) vaccine advisory committee . At that same time, a newly mandated report was released from the Food and Drug Administration that quantified the mercury compounds that had been introduced to foods and drugs in the United States . According to the report, children could receive up to 187.5 µg of mercury from vaccines alone by six months of age . The source of the mercury in vaccines was an ethylmercury compound called thimerosal, which is used to inhibit bacterial growth. Thimerosal was introduced to some vaccines in the early 20th century, after numerous deaths of children who had received vaccines from multi-dose vials containing bacterial infections . Thimerosal had been tested on laboratory animals, and relatively high levels had even been injected into adults without adverse consequences. Also, the ethylmercury in the preservative can be more easily eliminated from the human body than methylmercury, which is commonly found in environmental sources (e.g., bioaccumulation in fish). However, Halsey, out of an abundance of caution, pressured the AAP to address the mercury exposure from thimerosal. The resultant public statement, which attempted to appease Halsey while remaining acceptable to his numerous colleagues who opposed the action, was difficult to understand. In the statement, thimerosal amounts in vaccines were described as safe, yet the recommendation was still made to reduce those levels . Many people were understandably left confused and unsure about how to proceed.
Within a year, the AAP’s statement had inspired the parent of an autistic child to publish an article in a little-known journal that hypothesized a link between thimerosal and autism . In the following years, Mark Geier, and his son David published a number of studies that claimed to put forward empirical evidence supporting the notion that thimerosal did indeed cause autism. The chemist Boyd Haley and the biochemist Richard Deth independently put forth papers describing mechanisms by which the thimerosal could be causing autism. Columbia University researcher Mady Hornig released the results of a study she said demonstrated that thimerosal caused autism in mice . The argument linking thimerosal to autism seemed to be gathering momentum, and vocal supporters of such a connection soon emerged. Robert F. Kennedy wrote a high-profile article [later retracted] appearing in Rolling Stone and salon that claimed a link between thimerosal and autism. Politicians such as Joe Lieberman, John Kerry, and Dave Weldon spoke publicly about their concerns about the preservative . For many parents and other outside observers, the media, political, celebrity, and scientific attention was sufficient to generate concern and questions about the situation. By spring 2001, the success at reducing thimerosal levels to only trace amounts in nearly all childhood vaccines may have inadvertently fueled suspicions regarding the unsubstantiated link between the vaccine preservative and autism .
Red Flag | Lack of necessary science competence
Scientific information can be exceedingly difficult to evaluate given its highly technical and specialized nature. For that reason, policymakers and the public must know who are truly the authentic experts to trust. That is particularly the case given that a major characteristic of pseudoscientific ideas is that they are generally promoted by false or discredited experts. Sometimes, a lack of genuine expertise can be easily identified. For instance, politicians and celebrities almost assuredly lack a scientific background related to issues they may address. However, sometimes determining relevant expertise is more difficult. For example, while the Geiers have published a number of scientific papers, David Geier has only a bachelor’s degree in biology. A special master in a vaccine injury case deemed Mark Geier to be “a professional witness in areas for which he has no training, expertise and experience” . Mark Geier has also had his medical license revoked in several states for employing an autism treatment that involves injecting children with a drug that has been used by some states to chemically castrate sex offenders .
Kennedy, Kerry, Lieberman, and Weldon span the political spectrum from liberal to conservative. Why are all people, regardless of political orientation, capable of promoting and believing misinformation/disinformation?
The Centers for Disease Control and Prevention (CDC) was also examining the link between thimerosal and autism. In 2000, CDC experts met at Simpsonwood in Georgia to discuss the preliminary results of a study conducted by one of their epidemiologists, Thomas Verstraeten. Based on Verstraeten’s work, he had initially concluded that a link between thimerosal and some neurological problems might exist. However, experts at the Simpsonwood meeting pointed out several flaws in the work, which Verstraeten spent the next several years addressing. After doing so, the researcher concluded that no relationship existed between vaccines with thimerosal and autism . In 2003, epidemiological studies analyzing thousands of children over several decades in Sweden and Denmark all concluded that autism rates had significantly increased in those countries after thimerosal had been removed from vaccines there in the early 1990s   . After reviewing over 200 research articles related to the supposed link between thimerosal and autism, the Institute of Medicine (IOM) declared that the “epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism” . Seven years after thimerosal had been reduced to trace amounts in nearly all childhood vaccines in the United States, Schechter and Grether reported that autism rates had not decreased in California—a difficult outcome to explain if the vaccine preservative truly had been causing autism .
Nature of science connections
An advanced degree in the sciences, employment as a professor and even a rich publication history do not necessarily mean that a person should be considered an expert for a given issue. For example, the view of vaccines that a renowned geologist holds are likely no better informed than those of other members of the public. Relevant expertise related to each socioscientific issue is therefore a critical factor to consider when evaluating sources of information. However, even a relevant expert can hold a fringe view that is not actually well supported by the body of research in their field. The most trustworthy sources related to socioscientific issues are therefore generally relevant professional organizations whose position statements best represent the body of research conducted by the global community of experts in that field.
As evidence against a link between thimerosal-containing vaccines mounted, conspiracy theories began to arise. The CDC meeting in Simpsonwood became a focal point for some, with accusations that officials had covertly met there with Verstraeten to alter his results and coordinate the narrative that they would tell the public . Robert F. Kennedy’s aforementioned article accused officials of burying Verstraeten’s original study, and cast doubt on the CDC with a number of supposedly questionable ties to the pharmaceutical industry . A full-page ad accusing the CDC of a cover-up was placed in USA Today in 2006 (Figure 3). Some people moved beyond false accusations and began to threaten prominent figures associated with vaccinations and vaccine research. A person threatened to hang Paul Offit while he was on a federal advisory committee to the CDC, members of the IOM group that concluded that no link existed between autism and vaccines received threats that were significant enough to pressure one person to resign, and Sarah Parker, a professor of pediatrics, was harassed to such an extent that she stopped publishing about vaccines out of fear for the safety of her family .
The discussion surrounding vaccines and autism had changed. Within the scientific community, consensus had been reached: the preponderance of evidence, including those from comprehensive meta-analyses (e.g., Taylor et al. ) did not support the notion that either the MMR vaccine or vaccines containing thimerosal caused autism. Meanwhile, some attempts to support a link between vaccines and autism continued to spiral towards pseudoscience, with frequent discussions of conspiracy theories, references to non-experts in a manner that either explicitly or implicitly portrayed the research community as being more divided than it actually was, and selectively citing only a small subset of published studies, while ignoring the larger body of research.
Red Flag | Promoting conspiracy theories
When asked about the supposed link between vaccines and autism, Mark Geier told a Kansas newspaper, “This is the biggest cover-up in medical history” . Science is a series of protracted debates that involve people putting forth ideas, and then allowing all members of the community to test the arguments. Accusations of conspiracy theories are therefore often employed by people who lack the empirical evidence to prevail within the scientific community, and who instead attempt to erode trust in the information, researchers, or review process. The presence of such conspiracy theories is therefore a major warning sign of science misinformation/ disinformation.
Figure 3. A portion of a full-page ad taken out by anti-vaccine advocates in USA Today in 2006.
Conspiracy explanations are often elaborate and require at least hundreds of people to stay silent and/or never err in their alleged plot. What makes conspiracy theories appealing to many people? What reasons may explain why those holding onto conspiracy theories are difficult to persuade that their explanations are unlikely true?
The vast majority of parents are not members of the scientific communities that have investigated whether vaccines cause autism. The published articles appearing in science journals are often inaccessible both in terms of paywalls and the required technical knowledge necessary to decipher them. Conversely, readily available information on the internet that is written for parents often perpetuates distorted, pseudoscientific views. For example, the following passage is from the website of Natural News, whose content was banned from Facebook in 2019 for the use of misleading information :
As you may recall, Dr. Wakefield found himself embroiled in a vindictive war waged by the conventional medical cabal after spilling the beans on the potential gastrointestinal consequences of the combination measles, mumps and rubella vaccine, also known as MMR. Not long after being published in the peer-reviewed British Medical Journal (BMJ) back in 1998, Dr. Wakefield's game-changing, and completely credible, findings landed him in the crosshairs of the British and U.S. governments, the corrupt BMJ editorial team, and a certain malevolent journalist by the name of Brian Deer, all entities that clearly made it their mission to destroy Dr. Wakefield's career and livelihood. 
What are some warning signs that the above passage may contain misinformation/ disinformation?
The impacts of disinformation and pseudoscientific views about vaccination have been significant. Even prior to the COVID-19 pandemic, the World Health Organization listed vaccine hesitancy as one of the top ten threats to global health . From 1998 to 2003, the MMR vaccination rate in Britain dropped from 92% to 80% . During that same period, cases of measles increased from 56 to 440 in England and Wales —still far below pre-vaccine levels, such as the 693,803 cases that occurred there in 1955 . In the United States, rising non-medical vaccine exemptions have been associated with increasing cases of measles and pertussis , with 70% of the over 17,000 measles cases from 2001-2015 occurring in unvaccinated individuals . Decreasing levels of vaccination are particularly troublesome for the most vulnerable individuals within communities who cannot be vaccinated for medical reasons, and instead must rely on a high percentage of people around them to be vaccinated to inhibit transmission of diseases (i.e., herd immunity). Herd immunity levels vary by disease, and depend on factors such as how contagious the pathogen is. For example, measles, which is highly contagious, requires approximately 94% of people to be vaccinated to disrupt transmission . As of 2019, 90.8% of children two-years-old and younger in the United States had received at least one of their MMR vaccine doses , with clusters of vaccine-hesitant individuals leaving some communities with markedly lower rates .
Pseudoscientific information about vaccines has also impacted public health in other ways. Vaccine hesitancy due to unfounded autism concerns have diverted millions of dollars of money into research efforts that otherwise could have been used to investigate other aspects of autism. A wide-array of experimental, and often expensive, autism treatments have been marketed to desperate parents over the past two decades, including chelation therapy, hyperbaric oxygen chambers, and treatment with Lupron . Tests on the efficacy of chelation therapy, which supposedly treats autism by removing metals such as mercury from a child’s body, were discontinued by the National Institute of Mental Health in part due to concerns about the risks to children . In 2005, five-year-old Tariq Nadama was injected with such a chelating agent in an attempt to treat the autistic boy. Tragically, the drug bound to calcium in Tariq’s body, resulting in a fatal stoppage of his heart .
All parents, regardless of their opinion of vaccines, are seeking to do what is best for their children. The benefits of vaccinations seem abstract and distant when the devastating illnesses they prevent are no longer personally observed and common as they once were and could again be. At the same time, debates and media coverage inaccurately portray a divided medical community, and anecdotal accounts of children supposedly developing autism after vaccinations present an inflated sense of risk. As Ian and Linda Williams learned with their son, Alijah, the benefits of vaccinations are significant. Fortunately, in their case, after three weeks in intensive care, Alijah began to recover. But their son had to learn how to walk and eat again, and scars remain on his throat from the tracheotomy . The episode caused Ian and Linda to fully vaccinate their children, and they have attempted to warn other parents of the dangers of vaccine hesitancy as well. Ian Williams reflected on what had happened to Alijah by saying:
It was me that put my son in this situation. … Parents like us make the decision to not vaccinate on very little factual information about the actual consequences of the diseases—massive pain, disability and death—and a lot of non-factual, emotive information from the internet stating inflated figures on the frequency and severity of adverse reactions and conspiracy theories about ‘evil’ doctors, governments and drug companies .
Misinformation/Disinformation exacerbates the complexity of decision-making
Discerning science misinformation and disinformation can at times be very difficult. That is especially so when ideas are first raised, and the scientific community has not yet assessed those claims. Further complicating matters, scientific ideas that were once legitimate can transition into the realm of pseudoscience. Warning signs to help identify pseudoscientific information include a lack of competence among people who are presented as experts, creation of false legitimacy via creation of official sounding journals and institutes, the use of conspiracy theories, and appealing directly to the public with scientific information instead of utilizing typical peer-reviewed channels.
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