The World Health Organization has commended social media site Pinterest for its "leadership" in combating vaccine misinformation — believed to be a significant factor in the resurgence of vaccine-preventable diseases like measles.

"Misinformation about vaccination has spread far and fast on social media platforms in many different countries," said WHO chief Dr. Tedros Adhanom Ghebreyesus in a statement released on Wednesday.

"Social media platforms are the way many people get their information and they will likely be major sources of information for the next generations of parents."

The organization singled out Pinterest, however, for "only providing evidence-based information about vaccines to its users."

"We hope to see other social media platforms around the world following Pinterest's lead," the UN agency said.

In 2018, Pinterest — a site on which users (called "pinners") save visual content they like from other blogs or websites to their personal page — started blocking searches that contained terms such as "anti-vaccination" or "anti-vaxx," saying that they violated its community guidelines.

Pinterest ultimately stopped showing results for searches related to vaccines altogether "to prevent people from encountering harmful health misinformation," according to a news release the company issued on Wednesday.

The company will now start providing content about vaccination again — but only from "reliable" public health sources, including the WHO, the U.S. Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics.

"We also want to bring expert content onto Pinterest," said Ifeoma Ozoma, the company's public policy and social impact manager, in the release.

"We know we aren't medical experts, which is why we're working with professionals to inspire Pinners with reliable information about health."

Other social media giants, including Facebook and Twitter, have not been willing to block or remove vaccine misinformation, opting instead to reduce their visibility in users' feeds and search results. Last spring, Twitter announced a campaign called #KnowTheFacts, in which a notification pops up suggesting users searching for "vaccination" or "immunization" click through to immunization information pages at the U.S. Department of Health and Human Services or the Public Health Agency of Canada.

Back in May, both Facebook and Twitter told CBC News they had no plans to block anti-vaccination posts or ban known individuals or groups that spread anti-vaccination messages on their platforms. When asked on Wednesday if that position had changed, both companies referred CBC News back to their existing policies on combating vaccine misinformation.

Neither Facebook nor Twitter responded directly to the WHO's stated hope that other social media platforms would take actions similar to Pinterest.

This screenshot taken on Wednesday shows Pinterest's new effort to combat vaccine misinformation by only allowing content from 'reliable' sources, including the World Health Organization, the U.S. Centers for Disease Control and Prevention and the American Academy of Pediatrics. (Pinterest/Nicole Ireland/CBC News )

The principle of freedom of speech and not wanting to alienate users of their platforms are among the reasons social media platforms won't go that far, said Jonathan Jarry with McGill University's Office for Science and Society.

"Freedom of speech is not something to be curbed lightly," Jarry said.

But in this case, he believes Pinterest has landed on the right side of the debate.

"Misinformation on these emotional issues, like vaccinating children, it really plays to our most basic instincts. It makes us doubt good science, it makes us afraid. And it results in children suffering from entirely preventable diseases," Jarry said.

"So Pinterest has decided that on this important issue, public harm outweighs freedom of speech. And I agree."

The platform's move to re-introduce accurate information about vaccination, rather than just continue to avoid all vaccine-related content, was also a good decision from a public health perspective, Jarry said.

"Unfortunately, we're getting a lot of our health information from social media these days," he said. "People are turning to places like Facebook and YouTube and Pinterest for information on vaccines. And so I'm glad that there is good information on there."

Dr. Theresa Tam, Canada's chief public health officer, also expressed support for Pinterest's intiative.

"I applaud efforts by social media companies like Pinterest to increase access to evidence-based information on their platforms," Tam said in an emailed statement to CBC News.

"It is normal to have questions about vaccinations. There is an overwhelming amount of information on vaccination available from multiple sources, which could be confusing. Adding to the confusion, some of this information is contradictory, false or misleading," she said.

"Although most Canadians recognize the benefits of vaccines, not enough are being vaccinated. As a result, Canadians are still getting sick, and in some cases dying, from vaccine-preventable diseases."

According to the latest data available from the Public Health Agency of Canada, there have been 88 reported measles cases in Canada between Jan. 1 and Aug. 10, 2019. They were in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick and the Northwest Territories.

The disease, which is preventable by vaccine, was declared eliminated in Canada in 1998.