How Amazon became an engine for anti-vaccine conspiracy theories

A series of audits find the Everything Store’s algorithms recommending falsehoods about the coronavirus, vaccines, Dr. Fauci, and more.

How Amazon became an engine for anti-vaccine conspiracy theories
[Source photo: NikiLitov/iStock]

Search for “vaccines” on Amazon’s bookstore, and a banner encourages shoppers to “learn more” about COVID-19, with a link to the Centers for Disease Control. But the text almost vanishes amid the eye-catching book covers spreading out below, many of which are packed with dangerous falsehoods.


One top-ranked book promising “the other side of the story” of vaccine science is #1 on Amazon’s list for “Health Policy.” Next to it, smiling infants grace the cover of the top-selling book in “Teen Health,” co-authored by an Oregon pediatrician whose license was suspended last year over an approach to vaccinations that state officials said “placed many of his patients at serious risk of harm.” Another book, Anyone Who Tells You That Vaccines Are Safe and Effective Is Lying, by a prominent English conspiracy theorist, promises “the facts about vaccination — so that you can make up your own mind.” Studies have shown no link between vaccines and autism, for instance, but there are no warning notices or fact checks here. Instead, the book has over 1,700 five-star ratings and a badge: it’s #1 on Amazon’s list for “Children’s Vaccination & Immunization.”

Offered by small publishers or self-published through Amazon’s platform, the books rehearse the falsehoods and conspiracy theories that fuel vaccine opposition, steepening the impact of the pandemic and slowing a global recovery. Featured in search results or emblazoned with Amazon’s orange “bestseller” badges, the titles also illustrate how the world’s biggest store has become a megaphone for anti-vaccine activists, medical misinformers, and conspiracy theorists. That Amazon is a bookstore, not a social media platform, raises additional concerns: published books carry an apparent legitimacy that tweets cannot.

“Without question, Amazon is one of the greatest single promoters of anti-vaccine disinformation, and the world leader in pushing fake anti-vaccine and COVID-19 conspiracy books,” says Peter Hotez, a pediatrician and vaccine expert at the Baylor College of Medicine.


For years, journalists and researchers have warned of the ways fraudsters, extremists, and conspiracy theorists use Amazon to earn cash and attention. To Hotez, who has devoted much of his career to educating the public about vaccines, the real-world consequences aren’t academic. In the US and elsewhere, he says, vaccination efforts are now up against a growing ecosystem of activist groups, foreign manipulators, and digital influencers who “peddle fake books on Amazon.”

Anti-vaccine titles dominate search results for “vaccines”; the first autocomplete suggestion is “vaccines are dangerous” (Amazon)

Letting the truth loose

The Seattle giant is known for a relatively minimalist approach to policing content. The goal, founder Jeff Bezos said in 1998, was “to make every book available—the good, the bad and the ugly.” Customer reviews would “let truth loose.” Amazon’s algorithms and recommendation boxes would make it a place where, as it says on its website, “customers can find everything they need and want.” These days, they can publish everything they want, too: Amazon’s self-publishing platforms allow authors to make paper books, audio books, or e-books. The latter, Amazon says, “takes less than five minutes and your book appears on Kindle stores worldwide within 24–48 hours.”

Gradually, Amazon has taken a tougher approach to content moderation, and to a seemingly ceaseless onslaught of counterfeits, fraud, defective products, and toxic speech. The company says its automated and human reviewers now evaluate thousands of products a day to ensure they abide by its offensive content policies. For books, its prohibitions are brief and vague: material “that we determine is hate speech, promotes the abuse or sexual exploitation of children, contains pornography, glorifies rape or pedophilia, advocates terrorism, or other material we deem inappropriate or offensive.”


Sometimes that includes health misinformation. In March 2019, the company removed two films and two books that connected autism to vaccines shortly after Rep. Adam Schiff complained to Bezos that the store was “surfacing and recommending products and content that discourage parents from vaccinating their children.” The harm wasn’t theoretical, Schiff wrote, citing evidence that vaccine misinformation had helped fuel a recent measles epidemic in Washington. After the start of the coronavirus pandemic, Amazon said it removed over one million fraudulent products related to COVID-19, including “cures” like herbal treatments, prayer healing, and vitamin supplements. It also pulled an unknown number of books that pushed pandemic conspiracy theories, and added banners linking customers to credible information for virus-related search terms.

After January 6, amid a wave of content removals, Amazon pulled alt-right and QAnon merchandise for breaking its rules on hate speech. Later that month, it removed dozens of books promoting Holocaust denial, and finally removed the white supremacist novel The Turner Diaries. Amazon even banned Parler from its cloud service, citing the right-wing social network’s lax content moderation.

Despite its sweeps, however, Amazon is still flooded with misinformation, and helping amplify it too: A series of recent studies and a review by Fast Company show the bookstore is boosting misinformation around health-related terms like “autism” or “covid,” and nudging customers toward a universe of other conspiracy theory books.


Just a single click on an anti-vaccine book could fill your homepage with several other similar anti-vaccine books.”

Prerna Juneja and Tanushee Mitra

In one audit first published in January, researchers at the University of Washington surveyed Amazon’s search results for four dozen terms related to vaccines. Among 38,000 search results and over 16,000 recommendations, they counted nearly 5,000 unique products containing misinformation, or 10.47% of the total. For books, they found that titles deemed misinformative appeared higher in search results than books that debunked their theories.

“Overall, our audits suggest that Amazon has a severe vaccine/health misinformation problem exacerbated by its search and recommendation algorithms,” write Prerna Juneja and Tanushee Mitra in their paper, presented last month at the CHI Conference on Human Factors in Computing Systems. “Just a single click on an anti-vaccine book could fill your homepage with several other similar anti-vaccine books.”

Juneja and other researchers say Amazon needn’t remove conspiracy theory books, but it could keep them out of its search results and recommendations. “There is a need for Amazon to treat vaccine-related searches as searches of higher importance and ensure higher quality content for them,” she tells Fast Company.


Down the rabbit hole

In contrast with other big tech platforms like Facebook, Twitter, and YouTube, Amazon has no explicit public policy about misinformation, and does not provide public reports about its removal of content moderation, or disclose how many people it has hired to review content. When the Nathan Cummings Foundation, an activist shareholder group, recently called on Amazon to audit its approach to objectionable content, Amazon objected, telling the Securities and Exchange Commission it had already carried out a “review.” The review, it said, was a 550-word blog post reiterating its policies. In April, the SEC told Amazon it could ignore the proposal.

An Amazon spokesperson declined to answer questions on the record about how the company polices content, including the number of books it has removed over misinformation or conspiracy theories, how else it moderates or throttles books, and how it handles health-related titles in particular. Content moderation is “not something we tend to provide too much info on externally,” they said.

“Similar to other stores that sell books, we provide our customers with access to a variety of viewpoints, and our shopping and discovery tools are not designed to generate results oriented to a specific point of view,” the spokesperson said in a statement. They added that Amazon’s algorithms consider many factors when featuring books, including how often an item is purchased, its price and description, and availability.


Like any products on Amazon, or any content across social media platforms, anti-vaccine titles also benefit from an algorithmically-powered ranking system. And despite the company’s aggressive efforts to battle fraud, it’s a system that’s still easily manipulated through false reviews. Some titles can be downloaded for free, through Amazon’s Kindle and Audible subscription trials, which can ease coordinated purchases and drive up sales rankings. A similar strategy was used during last year’s election cycle, when four GOP-affiliated organizations spent more than $1 million mass-purchasing books written by GOP personalities, to boost them on bestseller lists, the Washington Post reported.

Amazon’s author pages and autocompleted search queries help keep certain ideas circulating: type “vaccines” into the search bar, for instance, and the first suggestion is “are dangerous.” Meanwhile, authors and publishers of anti-vaccine titles pay Amazon to boost their books. The top, sponsored result in a recent search for “autism” was a book co-authored by a prominent anti-vaccine author that pushes a discredited technique for communicating with people with autism; it’s also the #1 seller in “Audiology and Speech Pathology.”

From any given conspiracy theory book, Amazon’s algorithms also open up deeper rabbit holes, suggesting dozens of diabolical-sounding titles about medicine, climate science, elections, 9/11, and the Deep State. A study published in February by a group of researchers at the project examined 20 COVID-19 conspiracy theory books on Amazon and found the algorithms pointing customers toward increasingly extreme ideas, even when browsing non-conspiracy theory books. And a report published in April by the Institute for Strategic Dialogue, a London-based think tank focused on misinformation, found Amazon’s algorithms circulating COVID-19 and vaccine conspiracy theories, but also “cross-pollinating” them with books by other conspiracy peddlers and white nationalists.


For most customers, Amazon’s recommendations—”customers also shopped for,” “customers who bought this item also bought” and “frequently bought together” can be surprisingly helpful at best, or laughably useless at worst. But for conspiracy theorists, or for parents simply trying to learn more about vaccines, “these recommendations could serve as a gateway into a broader universe of conspiracy theories and misinformation, or to increasingly radical far-right and white nationalist content,” the ISD researchers wrote.

Recommendations on a page for a highly-ranked book on vaccines include other highly-ranked conspiracy theory books (Amazon)

Much of the uproar about misinformation has focused on Facebook, YouTube, and Twitter, but Amazon’s role deserves more attention, says Marc Tuters, an assistant professor of new media at the University of Amsterdam, who helped lead the study. The retailer sells half of all the books in the U.S. and its brand is highly trusted by consumers; one of its latest industry-shaking ambitions is to extend that brand into healthcare. As Rep. Schiff told Bezos in 2019: “As the largest online marketplace in the world, Amazon is in a unique position to shape consumption.”

But with its rules, algorithms, and customer reviews, “marketplace” may not capture the dynamics of Amazon’s platform, says Tuters; at times it’s also like “a de facto social media network.” “Amazon actively participates in creating a certain type of environment, in which certain things can thrive,” he says. That may be useful for selling sneakers or headphones, “but it may not be suited to an issue with widespread public health consequences.”


Grave consequences

As a source of information (or misinformation or disinformation), the medium presents its own risks. Books can carry an authority that a blog post or a viral video can’t. But they have no special claim to truth. While media outlets will fact check, publishers aren’t subject to the same legal liability, and often consider the research process too onerous. And absent fact-checks or expert reviews, Amazon’s customer reviews and ratings and bestseller lists are easily seen as proxies for quality. “We created category and subcategory best seller lists to highlight an item’s rank in the categories or subcategories where it really stands out,” the company’s website explains. As conspiracy books top Amazon’s bestseller charts for health-related topics, the recommendations and badges lend them more apparent credibility.

Search for “covid,” and one of the top results, Corona, False Alarm? boasts over 1,500 five-star ratings and a “bestseller” badge: it’s #1 in “Biostatistics” and “Health Law.” Published last summer in translation from the German, the book weaves together a series of outdated data and ludicrous claims, and concludes that the coronavirus “outbreak was never an epidemic of national concern.”

Amazon actively participates in creating a certain type of environment, in which certain things can thrive.”

Marc Tuters

Among the top results in a recent search for “Anthony Fauci,” a now-frequent target of right-wing conspiracy theories, are two titles from independent publisher Skyhorse Publishing, home to dozens of JFK conspiracy theory books, under an imprint for anti-vaccine activist Robert F. Kennedy Jr.’s nonprofit. There’s The Real Anthony Fauci: Big Pharma’s Global War on Democracy, Humanity, and Public Health, co-authored by Kennedy, whom Facebook removed from Instagram in February over his false claims. Another top-ranked book is Ending Plague, co-authored by Judy Mikovits, the discredited virologist featured in “Plandemic,” the pseudo-scientific video that a number of platforms purged last year. The books won’t be published by Skyhorse (and distributed by Simon and Schuster) until later this summer, but they’ve already earned best-seller badges: they are “#1 New Releases” in “Immunology” and “AIDS” respectively. (Mikovits’ previous book, also written with anti-vaccine blogger Kent Heckenlively, became a breakout Amazon best-seller last year, at one point beating out the long-awaited follow-up to the Twilight series; but their follow-up, The Case Against Masks, has been removed from Amazon.)


Another highly-ranked result is Fauci: The Bernie Madoff of Science…, published last year by the HIV-denialist Charles Ortleb, which was recently listed as Amazon’s #1 bestseller in “HIV & AIDS.” Available for free with an Audible or Kindle trial, and sometimes boosted in ads, the book is one of a handful on Amazon by Ortleb, who pushes the discredited notion that AIDS is caused by African swine fever. The theory fed a denialism that experts say contributed to hundreds of thousands of deaths.

“Books that promote medical misinformation are more dangerous than people realize,” says Michael Reale, a healthcare worker who worked with Ortleb during the early days of the HIV epidemic and once believed in his discredited theory.

“I’ve lost two close friends because they, believing this harmful nonsense, took themselves off the medications that were saving and prolonging their lives,” he says. “They read and believed his books. They believed in these long disproved theories.” It was only after they died that Reale realized his friends had fully abandoned their treatments in favor of Ortleb’s theories.


“It was like losing them a second time when I heard that.”

How to spread lies on Amazon—and how to slow them

Amazon’s algorithms aren’t optimized for conspiracy theories but for sales, fueling a virtuous cycle that benefits authors, publishers, and Amazon itself. The company typically takes a cut of around 15% for paper books and at least a one-third royalty on e-book purchases. And the recommendations help: In a 2012 experiment, the suggestions accounted for an increase of 8% to 20% in revenue. On its most recent earnings call, Amazon’s CFO credited the company’s investment in “new deep learning models to show more relevant sponsored products.”

The AI has no clue what those products say. Browse a number of highly-ranked search results for “Covid-19,” and the algorithms recommend a bestselling QAnon-inspired book that places the Rothschilds, George Soros, and the House of Saud in a New World Order “Triangle of Evil.” It now tops Amazon’s lists for “Political Philosophy” and “Religious Philosophy,” beating out classics by Michael Sandel, Marx, Huxley, and Plato.


“I am finally awake to the evil of the Cabal!” proclaims one of hundreds of five-star reviews. “I have followed the Seventeenth letter, and been awoke for a very long time,” another says. “This will be biblical.” It’s hard to say how many of these are real readers: According to Reviewmeta, which analyzes reviews for authenticity, two-thirds of the reviews appear suspicious.

Read more: How Amazon Helped Cambridge Analytica Harvest Americans’ Facebook Data

Amazon says it prohibits dubious accounts coordinating to leave false positive or negative reviews, and bars sellers from buying or incentivizing review fraud. But reviews are still regularly gamed, even by some of Amazon’s biggest merchants. Amazon manages to sweep away many fraudulent ratings, researchers said last year, but often not before they can influence buyers’ decisions.


To bypass Amazon’s content restrictions to begin with, sellers may avoid or misspell sensitive words or miscategorize books, a practice The Markup reported last year. Some COVID-19 conspiracy books have used a similar tactic, for instance by using alternative words for “vaccine,” says Tuters, of the University of Amsterdam.

To address the problem, Amazon could begin by “quarantining” conspiracy theory books from its discovery tools, says Tuters, echoing other researchers. Juenja, of UW, also suggests Amazon label authors known for spreading falsehoods, and place banners pointing customers to authoritative information on the pages of individual conspiracy theory books. The company could also hire experts to evaluate the health-related books that it sells.

“In the past, Amazon rolled out a feature [called] ‘verified purchase’ to curb the fake reviews problem on its platform,” she says. “Why not introduce a similar ‘verified quality’ or ‘verified claims’ tag with health-related products once they are evaluated by experts?”

‘I’ve pleaded with them to stop’

In the U.S., Amazon can operate its platform largely as it pleases. In countries like China and Saudi Arabia, it must abide by different rules: as Tuters and his colleagues found, none of the conspiracy theory books they studied are available on Amazon’s sites in those countries. But U.S. laws give the retailer wide latitude and generous protections to sell what it wants. When it does remove items, it’s often to earn goodwill from customers, or in response to journalists or the lawmakers who could remove its protections.

Amazon’s policing of 20 Covid-19 conspiracy theory books varies by local law, researchers found (

The result is a moderation process that often appears haphazard and unclear. Sometimes, questions from lawmakers may compel the company to remove products, as Amazon did after Rep. Schiff’s letter in 2019. But letters from Capitol Hill don’t always work. In March, after the company removed a 2018 book over its criticism of legal protections for transgender people, a trio of Republican senators sent an angry missive to Bezos. Amazon replied by informing the senators that “[w]e have chosen not to sell books that frame identity as a mental illness” without further explanation. The following month, dozens of Amazon employees sent their own letter, calling for the removal of a book they said was “full of misinformation” and had the “potential to hurt transgender youth.” Amazon’s moderation team disagreed.

Last June, journalist Alex Berenson told his 118,000 Twitter followers that Amazon had banned his self-published pamphlet, “Unreported Truths about COVID-19 and Lockdowns,” which argues that the mainstream media had inflated the threat. “Due to the rapidly changing nature of information around the COVID-19 virus, we are referring customers to official sources for health information about the virus,” Amazon’s digital publishing unit told Berenson. “Please consider removing references to COVID-19 for this book.”

An uproar ensued, and Elon Musk joined the fray. “Time to break up Amazon. Monopolies are wrong!” he tweeted. Amazon soon reinstated the book, saying it had acted “in error.” Thousands of five-star reviews later, the book and two subsequent volumes by Berenson are now certified Amazon bestsellers.

Amazon’s health misinformation challenges expand far beyond its digital bookshelves and it has already removed at least one million products touting fake COVID-19 cures. But like medical misinformation, the problem persists.

In February, the FDA sent a letter to Joseph Mercola, a controversial alternative medicine physician with a prominent Amazon presence, warning him that three drugs he was touting were “unapproved” and “misbranded” as COVID-19 treatments. Mercola eventually modified the language on his website, but not before claiming his legal problems were caused by, among others, “pharma-funded legislators” and Dr. Hotez, the pediatrician.

But the pills are still available on Mercola’s Amazon storefront. Also for sale is a book he co-authored last year that promises to show how the effectiveness of vaccines “has been wildly exaggerated and major safety questions have gone unanswered.” For months, the book, The Truth About COVID-19, has topped Amazon’s best seller lists for topics like “Political Freedom” and “Children’s Health,” and recently earned a rare blue badge: It was Amazon’s 9th best-selling non-fiction book overall.

Dr. Hotez has seen his own book, Vaccines Did Not Cause Rachel’s Autism, rise in Amazon’s rankings in recent years, and even reach the first page of results for “vaccines.” But after years of negative, sometimes vicious reviews by anti-vaccine advocates, his debunking is still buried among the conspiratorial books, including Mercola’s. And so he keeps sounding the alarm, hoping the world’s biggest store will listen.

“I’ve pleaded with them to stop this practice but they do not seem to care,” says Hotez. “I would do almost anything to get them to stop.”


About the author

Alex is a contributing editor at Fast Company, the founding editor and editor at large of Motherboard at Vice, and a freelance writer and producer with a focus on the intersections of science, technology, media, politics, and culture.