Pinterest, a digital platform popular with parents, took an unusual step to crack down on the proliferation of anti-vaccination propaganda: It purposefully hobbled its search box.
Type “vaccine” into its search bar and nothing pops up. “Vaccination” or “anti-vax”? Also nothing.
Pinterest, which allows people to save pictures on virtual pinboards, is often used to find recipes for picky toddlers, baby shower décor or fashion trends, but it has also become a platform for anti-vaccination activists who spread misinformation on social media.
It is an especially effective way to reach parents: 80 percent of mothers and 38 percent of fathers in the United States are on Pinterest, according to 2017 data from comScore. The company has more than 250 million monthly active users and is expected to go public this year.
Other companies like Facebook, YouTube and Twitter have also been infiltrated with misinformation about vaccines. But only Pinterest, as first reported by The Wall Street Journal, has chosen to banish results associated with certain vaccine-related searches, regardless of whether the results might have been reputable.
“Right now, blocking results in search is a temporary solution to prevent people from encountering harmful misinformation,” Jamie Favazza, a spokeswoman, said. The company said it was working with experts to develop a more tailored long-term approach.
The changes, which were not publicly announced, started in September and October.
Opposition to vaccinations can be traced to the introduction of the first vaccine in the 18th century. Over time most people accepted vaccines, and diseases that could be prevented by them declined. They declined so much, in fact, that the success of vaccines may have muted the dangers associated with those diseases.
The World Health Organization identified “vaccine hesitancy” as one of this year’s 10 notable threats to global health.
“I think this is stunning,” said Dr. Gregory A. Poland, director of the Mayo Clinic’s Vaccine Research Group in Rochester, Minn. “It shows the magnitude of the problem.”
Despite clear evidence that vaccines are effective and safe, some people still choose not to get vaccinated or to vaccinate their children, which has contributed to a surge in measles cases worldwide. In the United States, there have been five measles outbreaks this year and at least 127 individual cases.
One or two in 1,000 children who contract this highly contagious disease will die. Last year, measles killed 72 adults and children in the European region, where measles has reached its highest levels in two decades. While measles deaths are rare in developed countries, the illness can have severe lasting consequences, such as vision loss.
There are several reasons for vaccine hesitancy: worries about side effects, cost, moral or religious objections, fears about a debunked link to autism and lack of knowledge about immunizations.
“We’re just seeing all sorts of misinformation flying around on social media,” said Arthur L. Caplan, head of the Division of Medical Ethics at the New York University School of Medicine, who has been writing about vaccine ethics and policy for 25 years.
“Fake news. Fake science,” he said on Friday. “Everybody’s an expert.”
An analysis by The Daily Beast of seven Facebook pages that promote anti-vaccine posts found that the pages had bought a combined 147 Facebook ads that had been viewed millions of times. Most of them targeted women over the age of 25, it reported.
Last week, Representative Adam B. Schiff of California, a Democrat and chairman of the House Intelligence Committee, wrote a letter to Mark Zuckerberg, the chief executive of Facebook, asking what steps the company was taking to prevent anti-vaccine information from being recommended to users. He sent a similar letter to Sundar Pichai, the chief executive of Google, which owns YouTube.
“We’ve taken steps to reduce the distribution of health-related misinformation on Facebook, but we know we have more to do,” a Facebook spokeswoman said in a statement. “We’re currently working on additional changes that we’ll be announcing soon.”
The company said it was considering reducing or removing this type of content from recommendations and demoting it in search results.
Dr. Poland, an internist who has spent 35 years in the vaccine field, said he often encountered patients who relied on social media when researching health questions.
“I will explain to a patient in detail the answer to their question and they’ll look at me and say, ‘Yeah, but I saw on Facebook that …’” he said, his voice trailing off. “You just want to tear your hair out.”
YouTube said on Thursday that it started surfacing more authoritative content in late 2017 for people searching for vaccination-related topics, and that its algorithmic changes would become more accurate over time.
YouTube also said it does not permit anti-vaccine videos to show ads.
“We have strict policies that govern what videos we allow ads to appear on, and videos that promote anti-vaccination content are a violation of those policies,” a YouTube spokeswoman said on Friday. “We enforce these policies vigorously, and if we find a video that violates them we immediately take action and remove ads.”
The company said it was beginning to reduce recommendations for certain anti-vaccination videos and was collaborating with experts about providing more context during searches, such as information panels with links to third-party resources.
Twitter said it had no specific policy to stem the spread of misinformation about vaccines but that its real-time nature was a “powerful antidote.”
“We, as a company, should not be the arbiter of truth,” Katie Rosborough, a Twitter spokeswoman, said in a statement on Friday, adding that Twitter was working to surface the highest quality and most relevant content first.
For all of these companies, containing the spread of misinformation, particularly about something as emotionally charged as vaccines, will be a lasting challenge as they balance fears about censorship with the need to promote useful content, experts said.
“It’s a mess that I don’t see easily solved,” Dr. Poland said.