Verified by 
"Falsehood flies, and the Truth comes limping after it; so that when Men come to be undeceiv’d, it is too late; the Jest is over, and the Tale has had its Effect." —Jonathan Swift (1710)
Measles Outbreak 2019: State of Emergency
In the 1300s, the plague swept across Asia into Europe, claiming up to 200 million lives, including half the entire population of Europe and earning the moniker “The Black Death.” Not knowing its actual cause at the time, treatment consisted of blood-letting with leeches or applying frogs to plague lesions. In the 1600s, plague doctors treated infected patients by donning masks with bird-like beaks intended to shield them from “miasma” or “bad air.”
It wasn't until after the third major pandemic of plague in the 1800s that the French physician Alexandre Yersin discovered that its cause was a bacterium eponymously named Yersinia pestis. The first vaccine against Yersinia pestis was developed soon thereafter and with antibiotic treatments subsequently discovered in the 1940s, death from the plague is a relatively rare occurrence today.
Indeed, it’s often said that antibiotics and vaccines have been the most important scientific discoveries in the entire history of medicine, responsible for saving countless lives and preventing untold deaths. And yet, fast-forwarding to the present, we’re now in the midst of an emerging measles epidemic here in the US, with Washington state declaring a state of emergency last month with 50 confirmed cases, which has been described as “only the beginning.” Meanwhile, some 215 cases of measles have been confirmed in New York and New Jersey.
Measles, a viral illness easily transmitted by coughing and sneezing is one of the most highly infectious human diseases. The Center for Disease Control (CDC) states that more than 90% of “susceptible persons” will contract the illness if exposed. Who is “susceptible?” People—mainly children—who haven’t been vaccinated. With vaccination, the risk of infection with exposure drops from 90% to just 5%. Just so, after the widespread administration of the measles vaccine to infants in the 1970s, cases in the US dropped from several hundred thousand per year including several hundred deaths (death occurs in 1-2 out of 1000 cases) to the point of complete elimination in 2000.
Measles outbreaks in the past 20 years have occurred in isolated epidemics within the US, often started by travelers from out of the country and spreading within areas where vaccination rates have been low. Failing to protect children from virulent disease has been rooted in religious-based prohibitions (on the grounds that vaccines can contain products derived from pork or were originally developed from aborted fetal tissue1) and is symptomatic of the larger “anti-vaxxer” movement that is rooted in fears about vaccines causing autism or other health problems. Such fears have been taken seriously by enough legislators that 17 states allow non-medical exemptions to vaccination based on “philosophical” grounds (down from 18 after California removed its exemption following a 2015 measles outbreak at Disneyland). All but three states permit exemptions based on religious grounds.
With vaccine exemption laws in place, a large outbreak of measles occurred in 2014, mostly contained within an unvaccinated community of Amish in Ohio. This past year’s outbreak in New York and New Jersey has occurred mostly within the ultra-Orthodox Jewish community. But the problem now extends well beyond the insular preferences of some religious groups. In Washington state, the measles epidemic has been attributed to a “very aggressive anti-vaccination lobby in the Pacific Northwest” unrelated to religious practice.
In other words, it’s the “anti-vaxxers.”
In response to the growing danger and risk of death from measles, the New York Times editorial board issued a statement last month entitled, “How to Inoculate Against Anti-Vaxxers.” It claimed that “vaccine hesitancy is as American as can be,” noting that there are hundreds of thousands of infants and toddlers currently unvaccinated, and millions only partially vaccinated, in the US today (it’s a big problem in Europe and other countries too). It further quoted from an op-ed piece by Dr. Heidi Larson at the London School of Hygiene and Tropical Medicine published in Nature last year that suggested that the next major disease outbreak “will not be due to lack of preventative technologies [but to an] emotional contagion, digitally enabled” that could “erode trust in vaccines so much as to make them moot.”2 A subsequent response by the presidents of the American Academy of Pediatrics and the International Pediatrics Association joined in calling for an international effort to combat the “dangerous misinformation” that has made parents fear vaccines more than the diseases they prevent.
As of 2015, over 25% of US children 19-35 months old weren’t fully vaccinated according to medical guidelines.3 The number of nonmedical exemptions for vaccinations has been rising over the past decade in states where they’re allowed. Dr. Larson suggests that the scourge of vaccine misinformation underlying this disturbing must be challenged by dialogue, listening, and engagement. Therefore, instead of disparaging and mercilessly satirizing anti-vaxxers as online commenters recently did to a woman asking how to protect her unvaccinated child in the midst of the measles outbreak, let’s examine the anti-vaxxer phenomenon and try to understand why seemingly well-intentioned parents are increasingly holding fast to misbeliefs that place their children and others’ at grave risk of illness and death.
Vaccines Do Not Cause Autism
"In 1736 I lost one of my sons, a fine boy of four years old, by the smallpox taken in the common way. I long regretted bitterly and still regret that I had not given it to him by inoculation. This I mention for the sake of the parents who omit that operation, on the supposition that they should never forgive themselves if a child died under it; my example showing that the regret may be the same either way, and that, therefore, the safer should be chosen.” —The Autobiography of Benjamin Franklin, Benjamin Franklin (1791)
To attempt an understanding of anti-vaxxers, we need to begin by examining the basic science of and the clinical evidence for vaccines. Simply put, vaccines involve using an inactivated or attenuated infectious agent, or part of it, to stimulate the body’s natural immune response to develop antibodies against the real version of that agent. They’re a form of “primary prevention” against an infectious disease rather than a treatment for the disease itself. One of the first vaccines used in the US involved the use of cowpox to prevent smallpox infection in the late 1700s to fight smallpox — as noted in the quotation above, Founding Father Ben Franklin lamented his decision not to vaccinate his son against smallpox, a decision that he blamed for his son’s death.
Fears about vaccines and the rejection of government mandates to inoculate children based on religious and political grounds isn’t new and can be traced back as far as vaccine use in the US itself.1 In the modern era, objection to the combined “trivalent” measles, mumps, and rubella (MMR) vaccine began in the early 1990s and was fueled by the work of London-based physician and gastroenterology researcher Andrew Wakefield. Following two research publications implicating the measles virus as a cause of inflammatory bowel diseases like Crohn’s disease and ulcerative colitis,4,5 Wakefield and his colleagues followed up in 1998 with the publication of a case series describing 8 out of 12 children whose behavioral problems and loss of cognitive abilities “had been linked, either by the parents or by the child’s physician, with measles, mumps, and rubella vaccination.”6 This particular paper noted evidence of bowel inflammation (“ileocolonic lymphoid nodular hyperplasia”) in the children, but offered no evidence much less proof of any causal linkage between the MMR vaccine and autism. In 2000, Wakefield followed with another case series of 60 children with autism, Asperger’s syndrome, attention deficit hyperactivity disorder (ADHD), or schizophrenia who also had bowel inflammation, but this paper made no claim implicating the MMR vaccine.7 Still, outside of the published papers, Wakefield drew widespread public attention after holding a press conference calling for the replacement of the combination MMR vaccine with single “monovalent” vaccines, based on his claim that the trivalent vaccine caused “autistic enterocolitis.” Vaccinations rates dropped significantly around this time, both in Europe and here in the US.
In 2004, the Lancet issued a partial retraction of Wakefield’s 1998 study, following by a full retraction in 2010. The American Journal of Gastroenterology did the same for Wakefield’s 2000 study. Collectively, the retractions were based on findings of biased and misrepresented sampling methods, fraudulent claims, falsification of data, irreproducible results, and the identification of potential conflicts of interest.
In 2011, a series of articles in the British Medical Journal written by journalist Brian Deers detailed the basis for these claims including how prior to publishing his 1998 paper, Wakefield had received over £400,000 from a law firm looking for clients in a class action lawsuit against the makers of the MMR vaccine and had also applied for a patent for a “safer” monovalent measles vaccine to replace the trivalent MMR vaccine8). In 2010, the UK General Medical Counsel removed Wakefield from its register, effectively stripping him of his license to practice medicine. In its aftermath, some have called the Wakefield scandal “the most damaging medical hoax in 100 years.”1
Meanwhile, numerous studies by other researchers investigating an association between autism and the MMR vaccine — summarized in a 2014 meta-analysis of well over a million children entitled, “Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies” — have found no evidence of any such link.9
Unfortunately, in combination with the so-called “backfire effect” that suggests that correcting misinformation can sometimes have the opposite effect, the retractions of Wakefield’s papers and his professional sanctioning may have been too little, too late. He may have been thoroughly discredited within the medical field, but with a self-authored 2010 book, a 2016 propaganda film, and a high-profile romance with ex-supermodel Elle MacPherson in 2018, Wakefield has continued his claims, becoming the Messiah of the anti-vaxxer movement and lending it the false illusion of scientific merit.
In addition, notable celebrities, including Jenny McCarthy and Jim Carrey, Alicia Silverstone, Charlie Sheen, Bill Maher, Robert DeNiro, and current US President Donald Trump have become vocal anti-vaxxers along the way, spreading disinformation in interviews and on platforms such as the Oprah Winfrey Show. No surprise then that a 2015 Gallup Poll of 1015 US adults found that 52% were “unsure” if vaccines cause autism in children or that a 2018 Zogby Poll of 1,004 US adults found that while 90% of respondents felt vaccines were “very important” or “somewhat important” to health, over 25% lacked confidence in the safety of vaccines.
Understanding Anti-Vaxxers
Now that we understand the fraudulent “evidence” that has undermined people’s confidence in vaccines, let’s take a closer look at anti-vaxxers themselves. And lest you dismiss them offhand as “crazy” and “dangerous,” first ask yourself if you got the flu vaccine this winter. More than half of the Zogby Poll respondents didn’t last season — if you didn’t either, you might be an anti-vaxxer yourself!
Indeed, anti-vaxxers are a heterogeneous group with a wide range of beliefs. Maybe watching Jenny McCarthy on Oprah put just enough doubt in your head as a concerned parent that you opted out of giving the MMR vaccine to your child. Or maybe you opted out of vaccinating your children because living within the comfort of “herd immunity” resulting from many years of successful vaccination, you think the risk of something like measles or polio is small enough to justify the gamble. Or maybe you just think the hassle of getting the flu shot — which doesn’t always protect against the particular strain of flu that emerges each year — isn’t worth it because you think it won’t kill you, forgetting the risk you pose to those with weaker immune systems like your elderly grandparents, your children, or your friends and relatives undergoing chemotherapy for cancer.
Over the past few years, several studies have revealed more about the psychological underpinnings of anti-vaxxers. For example, research from 2015 found that anti-vaccination beliefs are more common among those who endorse spirituality as a valued basis for knowledge and prefer complementary alternative medicine over conventional medicine, leading its authors to conclude that “vaccination skepticism” results from a “cultural and psychological orientation” characterized by an “unwillingness to engage with scientific evidence.”10 If this is so, it helps to explain why anti-vaxxers can be resistant to the presentation of objective medical evidence that overwhelmingly supports the benefit against the risks of vaccination.
More recently, researchers at the University of Queensland investigated whether anti-vaccination attitudes could be explained by “motivated reasoning,” the process by which we come to believe things because we want to believe them, cherry-picking evidence to support that desire in the process.11 Administering a survey to 5,323 respondents across 24 countries, the investigators explored whether anti-vaccination beliefs were associated with different “attitude roots,” defined as “underlying fears, ideologies, worldviews, vested interests, and identity needs”12 that in this case underlie science-rejection. Of the “attitude roots” examined, the strongest association with anti-vaccination beliefs was the belief in other conspiracy theories (e.g. regarding the assassination of JFK, the death of Princess Diana, the existence of a New World Order, and the US government’s involvement in 9/11). Echoing earlier findings that belief in one conspiracy predicts belief in others,13 this suggests that anti-vaccination beliefs are conspiracy theories themselves. For example, many anti-vaxxers claim that the benefits and risks of vaccines are misrepresented by the likes of vaccine makers working in cahoots with the medical establishment and therefore not to be trusted.
Researchers at Stony Brook University performed an experiment that demonstrated that exposure to conspiracy theories about vaccines is more influential on those with pre-existing negative feelings about pharmaceutical companies and the news media.14 Importantly, both explicit conspiracy statements as well as more subtle suggestions about possible conspiracy increased conspiracy beliefs about vaccines. These findings support the idea that some anti-vaxxers are conspiracy theorists, convinced of the profit-driven evil of Big Pharma and physicians who are either duped by drug companies or profiting along with it. Of course, vaccine skepticism rooted in mistrust of the medical establishment would be at the very least ironic considering the real-life mini-conspiracy of the Wakefield scandal that spawned it.
In addition to conspiracy-based mistrust, Matthew Motta and his colleagues explored whether the Dunning-Kruger Effect — whereby those with the lowest levels of actual knowledge tend to have the greatest degree of overconfidence regarding self-rated expertise — might figure into anti-vaccination beliefs.15 Administering a survey to 1,310 US adults, they found that over a third of respondents believed they knew as much or more about the causes of autism than doctors and scientists and that such overconfidence was highest when respondents demonstrated low levels of actual knowledge and higher levels of misinformation about the relationship between autism and vaccines.
Replications of the Dunning-Kruger Effect among those with anti-science beliefs — a study was just published finding it among GMO skeptics16 — shouldn’t come as a surprise. After all, it’s almost tautological to say that those who reject scientific consensus in favor of misinformation have low levels of actual knowledge. Some have interpreted the finding to mean that overconfidence in personal expertise and belief in misinformation can be corrected through education, that is, by increasing actual knowledge. But that’s much easier said than done.
What You Don’t Know Can Hurt You
If what science denialists deny is the very premise that scientific knowledge is real knowledge, then they would be predictably resistant to efforts to correct misinformation. Indeed, research to date has been very discouraging in this regard, finding that attempts to dispel vaccine-autism myths through education do little to change anti-vaccination attitudes.
In 2014, Brendan Nyhan and colleagues published a study in which anti-vaccination attitudes among parents were countered by refuting claims about a vaccine-autism link and highlighting the dangers of not vaccinating by presenting information about the diseases the vaccines prevent, showing images of infected children, and providing a narrative about a mother hospitalizing her son with measles.
Not only were these strategies ineffective, they sometimes increased anti-vaccine beliefs via the back-fire effect.17 For example, when presented with information refuting the claim that vaccines cause autism, study subjects reported lower levels of agreement with that myth, but didn’t report any reduction in concerns about the risk of “serious side effects” from the MMR vaccine. Subjects who read a disease narrative reported heightened concerns about MMR side effects, while looking at images of children with measles, mumps, or rubella reported increased belief in vaccines causing autism.
These specific effects echo those of the University of Queensland study that found that in addition to belief in conspiracy theories, “heightened disgust reactions to needles, hospitals, and blood” were also associated with anti-vaccination beliefs.11 Taken together, these results suggest that reading disease narratives and seeing disease images may only trigger visceral reactions that are transferred onto existing anti-vaccination beliefs. In other words, attempts to educate by tapping into emotions could back-fire, by providing additional fuel for motivated reasoning.
A 2015 study replicated Nyhan’s finding that exposing people to information refuting the vaccine-autism myth did not decrease anti-vaccination attitudes.18 But in contrast to Nyhan’s disappointing results, the researchers demonstrated success in reducing general anti-vaccination attitudes by highlighting disease risk through informational warnings, a picture of an infected child, and a written narrative from a mother’s perspective. In addition to the use of combined interventions and measuring general rather than specific anti-vaccination attitudes, their positive results could be explained by the intervention being most helpful among “fence-sitters” who didn’t have strong feelings one way or the other about vaccines. A reanalysis of the data found that the study interventions didn’t significantly change the minds of those who would be better characterized as true anti-vaxxers,19 leaving open the question of whether doing so is possible in those with strong anti-science beliefs.
The Real Vaccine Conspiracy
As cases of measles and other preventable infectious diseases mount, those of us interested in changing the “hearts and minds” of anti-vaxxers are looking for novel approaches to dispel vaccine myths. As mentioned previously, Dr. Larson believes that “dialogue matters” and that listening to and engaging with anti-vaxxers is a necessary starting point. Christopher Swingle, a St. Louis doctor, has written that optimal results might depend on trust cultivated at the individual level within the doctor-patient relationship.20 Matthew Hornsey and Kelly Fielding, the University of Queensland psychologists who found a connection between anti-vaccination beliefs, conspiracy theories, and disgust reactions, have proposed that the motivated rejection of science must be countered with “jiu-jitsu persuasion” that acknowledges the “attitude roots” of anti-science beliefs in a nonjudgmental and nonadversarial way before attempting change.12
While “jiu-jitsu persuasion” sounds like a worthwhile tactic, Hornsey and Fielding specifically recommend that we appeal to anti-vaxxer fears about injections and medical interventions by highlighting the health risks of not vaccinating. As we’ve seen though, trying to convince parents to discount their vaccine-fears by highlighting the risks of not vaccinating might work for “fence-sitters,” but not for those with entrenched beliefs who have found the “evidence” to back them up from misinformation found online or by watching Wakefield’s documentary movie.
I’ve written before about how the “evidence” for the most fringe beliefs can be easily gathered at the click of a button through an internet search, creating a kind of “confirmation bias on steroids” (see my blog posts “Does the Internet Promote Delusional Thinking?" and “Fake News, Echo Chambers & Filter Bubbles: A Survival Guide"). This couldn’t apply more to anti-vaccination fears. Anna Kata, an anthropologist at McMaster University in Canada, has noted that 16% of total internet users sought information about vaccines online in 2006 and that over half of users believe “most” or “almost all” of what they find on “health websites.”21 In a 2009 study, she found that among the top 10 Google search results using the keyword “vaccination,” 71% were anti-vaccination sites. Kata calls the internet a “postmodern Pandora’s box” in which scientific truth is rejected and misinformation is conflated with information. In a post-modern world fueled by widespread online untruth, alternate facts have become the new facts (see my blogpost “The Death of Facts: The Emperor’s New Epistemology”) and anti-intellectualism has become the new normal.22
The “tactics and tropes” and conspiratorial rhetoric of vaccination websites and social media commentaries have been well-documented by Kata and more recently by Mark Davis at the University of Australia.23,24 In addition, David Broniatowski and colleagues performed an analysis of nearly 2 million Twitter tweets posted from 2014 to 2017 to determine what role "bots" (web robots that run automated tasks over the internet), "content polluters" (accounts that spread malware and other unsolicited commercial content), and Russian "trolls" (real people who misrepresent their identity and post content intended to “stir the pot”) play in online discussions about vaccines.”25 They found that bots, content polluters, and Russian trolls were much more likely than the average Twitter user to post about vaccines. Content polluters were 75% more likely to post anti-vaccine content, suggesting they're exploiting the popularity of anti-vaccine memes as “clickbait.” Russian trolls posted both pro- and anti-vaccination tweets, consistent with the intent to sow discord among the American populace. This study highlights how much of the vaccine misinformation posted on social media is not only false, but as Broniatowski says, “weaponized” with the deliberate intention of deception and fomenting unrest.
And there it is — what every good conspiracy theory needs... the real conspiracy about vaccines. The “evidence” that sparked the modern anti-vaxxer movement in the first place was started by a doctor with a significant financial interest in replacing the MMR vaccine with a vaccine that he developed himself and was building a business around. He fabricated data in a small handful of patients to promote a bogus link between vaccines and autism. Despite being thoroughly discredited, and despite subsequent studies based on millions of people showing no association of vaccination and autism, “the most damaging medical hoax in 100 years" continues to raise just enough doubt among parents to forego vaccinating their kids. The fear of such parents, including worried mothers and fathers living in a helicopter parenting world, where the pressure to remove all risk and suffering from our children’s lives is considerable, as well as the parents of children with autism who are by their own description “vulnerable [and] looking for answers,”8 has been exploited by anti-vaxxer organizations with their own vested interests and deceptive online forces in the form of spambots and Russian trolls operating under direction of the Kremlin. Adding insult to injury, the President of the United States created a ‘Vaccine Safety Task Force” in 2017 and appointed Robert F. Kennedy, a lawyer whose qualifications include having written several laypress articles and books based on false information about the mercury content of vaccines, as its chair. While thankfully nothing has come of the task force to date, suffice it to say that the anti-vaxx conspiracy has infiltrated the highest levels of government.
If that’s enough “jiu-jitsu persuasion” to convince anti-vaxxers, I don’t know what is.
And the end result of this real-life conspiracy theory? Children are getting diseases that were previously eradicated. Some of them are dying.
Maybe, in the end, coming face-to-face with death — and I mean really face-to-face like Ben Franklin did, not just through written pamphlets, images, and stories — is what it will take to change anti-vaxxer beliefs. In the wake of the measles outbreak in Washington state, the demand for vaccines has since skyrocketed, increasing by up to 500% in some areas. Like in California, a measure has been introduced to remove the personal belief exemption for the MMR vaccine in the state.
So, there’s hope yet in changing the hearts and minds of anti-vaxxers.
But then again, it's just as likely that we'll soon start hearing conspiracy theorists claim that the children with measles and their parents are “crisis actors” in a “false flag” operation being run by the CDC.
To learn more about anti-vaxxers and vaccine hesitancy, read Vaccine Hesitancy: From Misinformation to Conspiracy Theory.
References
1. Hussain A, Ali ZS, Ahmed M, et al. The anti-vaccination movement: A regression in modern medicine. Cureus 2018; 10(7):e2919.
2. Larson HJ. The biggest pandemic risk? Viral misinformation. Nature 2018; 562:309.
3. Olive JK, Hotez PJ, Damania A, et al. The state of the antivaccine movement in the United States: A focused examination of nonmedical exemptions in states and counties. PLOS Medicine 2018; 15(6): e10022578
4. Wakefield AJ, Pittilo RM, Cosby SL, et al. Evidence of persistent measles infection in Crohn’s disease. Journal of Medical Virology 1993; 39:345-353.
5. Thompson NP, Montgomery SM, Pounder RE, Wakefield AJ. Is measles vaccination a risk factor for inflammatory bowel disease? The Lancet 1995; 345:1071-1074.
6. Wakefield AJ, Murch SH, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet 1998 [RETRACTED].
7. Wakefield AJ, Anthony A, Mursch SH, et al. Enterocolitis in children with developmental disorders. The American Journal of Gastroenterology 2000 [RETRACTED].
8. Deer B. How the vaccine crisis was meant to make money. BMJ 2011; 342:c5258 https://www.bmj.com/content/342/bmj.c5258
9. Taylor LE, Swerdfeger AL, Eslick GD. Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine 2014; 3623-3629.
10. Browne M, Thomson P, Rockloff MJ, et al. Going against the herd: psychological and cultural factors underlying the ‘vaccination confidence gap.’ PLOS One 2015; 10(9):e0132562.
11. Hornsey MJ, Harris EA, Fielding KS. The psychological roots of anti-vaccination attitudes: A 24-nation investigation. Health Psychology 2018; 37:307-315.1
12. Hornsey M, Fielding KS. Attitude roots and jiu jitsu persuasion: Understanding and overcoming the motivated rejection of science. American Psychologist 2017; 72:459-473.
13. Goertzel T. Belief in conspiracy theories. Political Psychology 1994; 15:731-742.
14. Lyons B, Merola V, Reifler J. Not just asking questions: effects of implicit and explicit conspiracy information about vaccines and genetic modification. Health Communication 2018; published online October 11, 2018.
15. Motta M, Callaghan T, Sylvester S. Knowing less but presuming more: Dunning-Kruger effects and the endorsement of anti-vaccine policy attitudes. Social Science and Medicine 2018; 211:274-281.
16. Fernbach PM, Light N, Scott SE, et al. Extreme opponents of genetically modified foods know the least but think they know the most. Nature Human Behavior 2018; published online January 14, 2019.
17. Nyhan B, Reifler J, Richey S, et al. Effectiveness messages in vaccine promotion: A randomized trial. Pediatrics 2014; 133:e835-e842.
18. Horne Z, Powell D, Hummel JE, et al. Countering antivaccination attitudes. Proceedings of the National Academy of Science 2015; 112:10321-10324.
19. Betsch C, Korn L, Holtmann. Don’t try to convert the antivaccinators, instead target the fence-sitters. Proceedings of the National Academy of Science 2015; 112:E6725-E6726.
20. Swingle CA. How do we approach anti-vaccination attitudes? Missouri Medicine 2018; 115-180-181.
21. Kata A. A postmodern Pandora’s box: Anti-vaccination misinformation on the internet. Vaccine 2010; 28:1709-1716.
22. Motta M. The dynamics and political implications of anti-intellectualism in the United States. American Politics Research 2018; 46:465-498.
23. 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; 30:3778-3789.
24. Davis M. ‘Globalist war against humanity shifts into high gear’: Online anti-vaccination websites and ‘anti-public’ discourse. Public Understanding of Science 2018 (in press); published online December 10, 2018.
25. Broniatowski D, Jamison AM, Qi S, et al. Weaponized health communication: Twitter bots and Russian trolls amplify the vaccine debate. American Journal of Public Health 2018; 108:1378-1384.
