In the first few hours of a newborn’s life, doctors administer a vitamin K shot. This is because infants are born without enough of the vitamin, and the baby needs a boost to prevent any potential bleeding.

This is a routine practice—ask your pediatrician, your obstetrician, or the CDC. “Babies are born with very low stores of vitamin K, and without the Vitamin K shot ... they do not have enough Vitamin K in their blood to form a clot,” the CDC says on its website.

But new parents who turn to search engines to understand the practice will find an aberrant—and dangerous—strain of thinking. Google “vitamin K shot” and the first result advises “Skip that Newborn Vitamin K Shot.” It isn’t until below the fold—the fourth result—that the CDC website appears.

Renee DiResta (@noUpside) is an Ideas contributor for WIRED, the director of research at New Knowledge, and a Mozilla fellow on media, misinformation and trust. She is affiliated with the Berkman-Klein Center at Harvard and the Data Science Institute at Columbia University.

This is what Michael Golebiewski at Bing calls a "data void," or search void: a situation where searching for answers about a keyword returns content produced by a niche group with a particular agenda. It isn’t just Google results—keyword voids are happening on social too. The most shared articles about vitamin K on Facebook are anti-vax, and the CrowdTangle analytics platform shows those articles are reaching an audience of millions. YouTube results are no better; several of the top 10 results feature notable immunology expert Alex Jones.

There’s an asymmetry of passion at work. Which is to say, there’s very little counter-content to surface because it simply doesn’t occur to regular people (or, in this case, actual medical experts) that there’s a need to produce counter-content. Instead, engaging blogs by real moms with adorable children living authentic natural lives rise to the top, stating that doctors are bought by pharma, or simply misinformed, and that the shot is risky and unnecessary. The persuasive writing sounds reasonable, worthy of a second look. And since so much of the information on the first few pages of search results repeats these claims, the message looks like it represents a widely-held point of view. But it doesn’t. It’s wrong, it’s dangerous, and it’s potentially deadly.

Since so much of the information on the first few pages of search results repeats these claims, the message looks like a widely-held point of view.

Search isn’t the whole story, of course. Social reinforcement from trusted friends is critically important, particularly when trust in authorities is in crisis. The vitamin K question pops up frequently on pregnancy forums and in mommy groups, particularly in the groups that focus on what’s come to be called “natural parenting”. These communities opt out of vaccines at a higher rate, and a number are now also skipping the vitamin K shot: two studies have found refusal rates are higher at birthing centers than hospitals.

Natural parenting groups are very common on Facebook—a quick search turns up dozens with just the keyword “natural.” These groups boast tens of thousands of members, organized regionally and sometimes by an additional interest. Most of the discussions in these communities revolve around routine parenting questions, the kind that can incite small flame wars but are ultimately just a matter of preference. However, the recommendation engine knows that there’s a link between “natural” parenting and the antivax movement: join a natural parenting group and you’ll see suggestions for homemade baby food, backyard chicken-raising, organic homemaking—and dozens of anti-vaccine groups.

The anti-vaccine group that the recommendation engine most frequently pushes to me personally has 130,000 members. It recently ran a GoFundMe that raised $10,000 for a paid Facebook ad campaign to target new parents with stories of SIDS deaths that they are claiming were caused by vaccines: “Vaccines Kill Babies Campaign—Parents Must Know Vaccination Is NOT Safe.” According to the group’s blog, the ad campaign is currently live, with ads targeting men and women with the interest “Pregnancy and Parenting.” And one of the posts they’re paying to boost with the GoFundMe money specifically claims that vitamin K can kill newborns: “If you are on the fence about vaccination, read this story, do more research, and join our Facebook group to talk with other parents. Your child's life depends on it.” The top comment is from a new mother, who’s tagged her friend: “Bit worried after going on this site what do u think.” The friend reassures her, but members of the group join the comment thread, pushing her to join their community to "learn the truth."

The tactic of paying to push manipulative narratives isn't new, nor is it unique to anti-vaxxers. Last year, The New York Times wrote about climate-denier groups that have purchased Google's AdWords to surface sites propagating claims that global warming is a hoax. I've written about recommendation engines that push radical news and information to people on YouTube and Facebook. This has led to entire organizations, like Snopes and FactCheck.org, devoting more resources to combating misinformation. But it's hard to make corrections go viral.