Congressman Adam Schiff is putting pressure on Amazon to curb the spread of vaccine misinformation in its online store. Misinformation around vaccines — like the debunked myth that it causes autism — has led to some children in the United States not getting vaccinated, and is seen by experts as a ‘major contributor’ to recent measles outbreaks.

Schiff’s letter to Amazon CEO Jeff Bezos follows two others letters Schiff sent to Google head Sundar Pichai and Facebook’s Mark Zuckerberg. In all three, Schiff criticized the platforms for serving up anti-vaccine propaganda where people look for information about vaccines. He also criticized Amazon for accepting paid advertising for anti-vaccine media. “Every online platform, including Amazon, must act responsibly and ensure that they do not contribute to this growing public-health catastrophe,” Schiff wrote.

“Every online platform, including Amazon, must act responsibly.”

The letter references a recent report from CNN that revealed that the vast majority of top search results for “vaccine” on Amazon provide anti-vaccination misinformation. CNN also reported that Amazon accepts paid advertisements for promoting anti-vaccine media. Right at the top of the “vaccine” search results is an ad for the free Kindle e-book Vaccines on Trial that fear-mongers about the safety and efficacy of vaccines. (To be fair, there’s also an ad for the $259.19 Kindle edition of the massive, authoritative, evidence-based textbook Plotkin’s Vaccines.)

Scrolling down the search results turns up a mix of ardently anti-vax misinformation and more subtle books that nevertheless encourage doubt about vaccines. The film Vaxxed falls into the first category and on Thursday evening sat right at the top of the list. It’s directed by the disgraced doctor Andrew Wakefield, who is responsible for the thoroughly debunked misconception that vaccines cause autism. (By Friday afternoon, Buzzfeed News reporter Caroline O’Donovan discovered that Vaxxed no longer ranked at the top of the search results, and appears to no longer be available for streaming on Amazon.)

“When we’re making decisions about medicine, we typically look to the light of science.”

In the more subtle category are books like The Vaccine-Friendly Plan that advocate for parental choice around vaccines — a euphemism for parents delaying or opting out of vaccinating their kids. Changing or delaying a kid’s vaccine schedule is not recommended by the American Academy of Pediatrics unless medically necessary. “You can go to Amazon and ask any question and get led to a bunch of different ideas,” says Wendy Sue Swanson, a pediatrician, vaccine expert, and spokesperson for the American Academy of Pediatrics. “But when we’re making decisions about medicine, we typically look to the light of science.” (Her book, Mama Doc Medicine, does not appear on the first page of search results.)

Similar results also crop up when you search “vaccination,” The Verge discovered — and these search results don’t include an ad for a vaccine textbook at the top. Presented with these titles, it can be difficult to separate fact from fear-mongering, particularly when fact is buried so far down the page. “Most parents are genuinely trying to do the right thing for their kids, and many are misinformed, frightened, or (more often) both,” wrote science journalist Tara Haelle in an email to The Verge.

“Most parents are genuinely trying to do the right thing for their kids.”

Haelle’s own, evidence-based book for young adults, Vaccination Investigation: The History and Science of Vaccines, comes up ninth in the “vaccination” search results. Though Haelle is not particularly concerned about her own book’s placement, she is concerned that non-evidence-based books are burying ones containing accurate data. “While I realize Amazon’s algorithms are based on popularity and other user characteristics, the end result of the algorithm is to lead parents astray with more misinformation,” she says.

The lists are particularly jarring since Amazon has been moving into the health space with a joint healthcare venture with Berkshire Hathaway and JP Morgan Chase and its purchase of online pharmacy PillPack. Yet when it comes to the algorithm that serves up search results about vaccinations for the retail arm of the company, Amazon has nothing to say on the record. Instead, Amazon suggested The Verge might find its content guidelines helpful: “As a bookseller, we provide our customers with access to a variety of viewpoints, including books that some customers may find objectionable. That said, we reserve the right not to sell certain content, such as pornography or other inappropriate content.”

“The end result of the algorithm is to lead parents astray with more misinformation.”

For experts, the issue isn’t that anti-vax books and films are objectionable: it’s that they could be harmful for public health. People who are too young or too sick to be vaccinated rely on everyone around them being vaccinated to prevent the spread of potentially deadly disease. Parental fears around vaccines that are stoked by misinformation can erode that protection. “Amazon has to take some responsibility of selling products that are dangerous to child health, which is what they’re doing,” says Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and author of Vaccines Did Not Cause Rachel’s Autism.

Diseases targeted by vaccines are dangerous — especially for children. During an outbreak in 1964 and 1965, the rubella virus killed 2,000 babies and caused 11,000 miscarriages, according to the Centers for Disease Control and Prevention. These days, thanks to the measles, mumps, and rubella (MMR) vaccine, the CDC is only notified about 10 cases in the US each year. Measles used to hospitalize 48,000 people and kill between 400 and 500 people in the US annually. Now, it’s theoretically eliminated in the US, but crops up and spreads in pockets of unvaccinated people — like right now, in Washington state.

“Amazon has to take some responsibility of selling products that are dangerous to child health.”

Amazon’s search results aren’t the only part of the site serving up vaccine misinformation; its bestseller list for “vaccinations” is, too. Hotez noticed this when he was looking at the page for his own book, which is about being both a vaccine researcher and the parent of an autistic child. A link underneath the product details for Vaccines Did Not Cause Rachel’s Autism connected to Amazon’s “Vaccination” bestsellers list. (After The Verge asked about it, the link looks to have disappeared from the book’s page — but it’s still possible to find the “Vaccinations” bestseller list.)

When Hotez clicked to see how his book ranked, he saw a few evidence-based books, including his own. But there were also books peddling fears about vaccines. An Amazon spokesperson tells The Verge that this bestseller list isn’t curated. “It simply reflects the books customers are purchasing.”

“Stop being the enabler.”

Kathryn Edwards, a professor of pediatrics at the Vanderbilt University School of Medicine, is one of the editors of the authoritative textbook Plotkin’s Vaccines. She isn’t certain that policing Amazon’s offerings is the way to go. “That’s not my place to decide what their business is,” she says. “If it’s not on Amazon, it will be at a bookstore.” She sees her role as helping people learn what’s fact and what’s fear-mongering. “I just want to make sure that people know how to choose and how to interpret legitimate and authoritative research and publications that are not,” she says.

Amazon isn’t alone. Other tech giants like Facebook and Google have also recently been called out after The Guardian reported that anti-vaccine misinformation was proliferating on the platforms. And Hotez, for one, told The Verge that they and Amazon should hire chief scientific officers who can evaluate the content these sites offer up. “Stop being the enabler,” he says. People can still find anti-vax content online. They can still rent or buy the film Vaxxed, for instance, on the Vaxxed website, he says. “They don’t need to use Amazon for it.”

Updated 3:20PM Friday March 1st, 2019: Updated with a quote from Tara Haelle and to include the news that Vaxxed no longer appears in Amazon’s search results for “vaccines” or “vaccination”, and is not available for streaming on Amazon.