University of Washington researchers say Amazon’s algorithms spread vaccine misinformation

The pandemic has unleashed a barrage of online misinformation that’s reinvigorated the anti-vaccine movement. Despite the fact that multiple COVID-19 vaccines are approved and beginning to be made available to the public, only two-thirds of Americans say they’ll try to get vaccinated, according to a CNN poll. As governments work toward distributing vaccines, health experts worry that reluctance could make it difficult to achieve herd immunity. Unfortunately, the algorithms powering search engines haven’t traditionally been designed to take into account the credibility and trustworthiness of medical information.

The coauthors of a recent study argue this is particularly true of Amazon, which has faced criticism for failing to regulate the health-related products on its platform. According to the University of Washington researchers, who have affiliations with the The Information School at the University of Washington, their audits reveal Amazon hosts a “plethora” of health misinformative products belonging to categories including books, ebooks, apparel, and health and personal care. They also claim to have found a “filter-bubble” effect in Amazon’s recommendations where recommendations of misinformative health products contain more health misinformation.

“Several medically unverified products for coronavirus treatment, like prayer healing, herbal treatments and antiviral vitamin supplements proliferated Amazon, so much so that the company had to remove 1 million fake products after several instances of such treatments were reported by the media,” the researchers wrote in their paper. “The scale of the problematic content suggests that Amazon could be a great enabler of misinformation, especially health misinformation. It not only hosts problematic health-related content but its recommendation algorithms drive engagement by pushing potentially dubious health products to users of the system.”

The researchers conducted two sets of experiments in May and August to determine the extent to which Amazon might be promoting health misinformation about vaccines. In the first — an “unpersonalized” audit — they used information retrieval metrics to measure the amount of health misinformation users were exposed to when performing for vaccine-related searches. In particular, while logged in as a guest to minimize the influence of personalization algorithms, they canvassed the results of 48 searches belonging to 10 popular vaccine-related topics including “HPV vaccine,” “immunization,” and “MMR vaccine and autism.”

The researchers ran the audit for 15 consecutive days, sorting the results across five different Amazon filters each day: Featured, Price Low to High, Price High to Low, Average Customer Review, and Newest Arrivals. They annotated the resulting 36,000 search results and 16,815 product page recommendations for their stances on health misinformation — i.e., whether they promoted, debunked, or were neutral regarding vaccinations — for a final dataset totaling 4,997 annotated Amazon products.

The second audit — a “personalized” audit — looked at the impact of a customer’s behavioral history on the amount of misinformation returned in search results, recommendations, and auto-complete suggestions. As the researchers note, Amazon history covers a weeklong period of actions including searching for products, searching and clicking, adding to cart after searching and clicking, searching on third-party websites like Google, and more.

After analyzing the results from both audits, the researchers found that search results returned for many vaccine-related queries contain large number of misinformative products, leading to what they characterize as “high misinformation bias.” In addition, misinformative products were ranked higher than “debunking” products, and customers performing actions on misinformative products were presented with more misinformation in their homepages, product page recommendations, and prepurchase recommendations, the researchers say.

“Many search engines and social media platforms employ personalization to enhance users’ experience on their platform by recommending them items that the algorithm thinks they will like based on their past browsing or purchasing history. But on the downside, if not checked, personalization can also lead users into a rabbit hole of problematic content,” the researchers wrote. “Our analysis … revealed that an echo chamber exists on Amazon where users performing real-world actions on misinformative books are presented with more misinformation in various recommendations. Just a single click on an anti-vaccine book could fill your homepage with several other similar anti vaccine books. There is an urgent need for the platform to treat vaccine and other health related topics differently and ensure high quality searches and recommendations.”

For its part, Amazon recently said in a corporate blog post that during 2020, it reviewed almost 10,000 product listings a day to ensure compliance with its policies and removed over 2 million products for violating its offensive or controversial guidelines. More than 1.5 million of these products were identified, reviewed, and removed proactively by automated tools, according to Amazon — often before being seen by a customer.

“We exercise judgment in allowing or prohibiting listings, and we keep the cultural differences and sensitivities of our global community in mind when making a decision on products,” Amazon wrote. “We strive to maximize selection for all customers, even if we don’t agree with the message or sentiment of the product itself. Our offensive and controversial products policy attempts to provide a clear and objective standard against which to measure the products we permit in our store.”

The researchers suggest as one potential solution a “bias meter” that could signal the amount of misinformation present in vaccine-related  search results. They also urge Amazon to stop promoting health misinformative books via sponsorships — the researchers found 98 misinformative products in the sponsored recommendations they annotated — and to introduce a label for health-related products that have been evaluated by experts. Moreover, they recommend that the platform account for misinformation bias in its search and recommendation algorithms to reduce the exposure to misinformative content.

“Our investigations revealed that Amazon’s algorithm has learnt problematic patterns through consumers’ past viewing and buying patterns,” the researchers wrote. “Our study … provides a peek into the workings of Amazon’s algorithm and has paved way for future audits that could use our audit methodology and extensive qualitative coding scheme to perform experiments considering complex real world settings.”

The researchers aren’t the first to uncover the presence of anti-vaccination content on Amazon. In May, CNN found listings and advertisements for books and movies promoting vaccination misinformation including VAXXED: From Cover-Up to Catastrophe, which was dropped from the Tribeca Film Festival in 2016 following an outcry. Amazon removed the anti-vaccine documentaries from its Prime Video service after CNN published its report.


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