Pinterest is taking on the anti-vaxxer movement by making sure searches for vaccination information only return results from authoritative health experts.

"Now when you search for 'measles,' 'vaccine safety' and other related health terms, you can explore reliable results about immunizations from leading public health organizations," Pinterest's public police manager Ifeoma Ozoma said in a Wednesday announcement.

The change means you'll encounter pro-vaccine information on Pinterest from groups such as the World Health Organization (WHO) and the Centers for Disease Control and Prevention. At the same time, none of the search results will include user-generated content such as recommendations or comments.

"We also won't show ads. We're taking this approach because we believe that showing vaccine misinformation alongside resources from public health experts isn't responsible," added Pinterest, which has 291 million users worldwide.

Last year, the social media site stopped showing results for searches on vaccines to prevent users from encountering anti-vaccination posts, saying the content amounted to "harmful health misinformation."

Other social media services including Facebook and YouTube have been tackling anti-vaccine information by making it harder to find. However, Pinterest has been taking things further by trying to remove user accounts found spreading anti-vaccine content, declaring the activities as a violation of its community guidelines, which prohibits "harmful advice."

In addition, Pinterest said it noticed another problem with vaccine information: "Experts have shown there's a data void when it comes to reliable information about vaccines—there's a greater distribution of vaccine misinformation than information. In short, anti-vaccine content is contagious," Ozoma said in yesterday's post.

The dearth of reliable vaccine information is why Pinterest is steering the company's search function to the leading health organizations. The change is already rolling out in English on Pinterest's website and mobile apps. "Ultimately, we want to bring authoritative results to more Pinners in more places, because there's nothing inspiring about harmful health misinformation," Ozoma said.

The new policy has received support from the WHO and the US Surgeon General. Anti-vaccination supporters and free-speech advocates, on the other hand, have been deriding the change as Pinterest becoming the "thought police."

Still, the rise of the anti-vaxxer movement has coincided with countries including the US experiencing a rise in measles outbreaks. On Thursday, the WHO announced that four European countries including the UK lost their measles elimination status due to the outbreaks.