The announcement comes just two days after Ethan Lindenberger, an Ohio teenager, told a U.S. Senate committee he defied his parents to get vaccinated despite growing up in an anti-vaccine, or "vaccine-hesitant" home.
He told senators on Tuesday that misinformation distributed, particularly on Facebook, puts children at risk.
"Certain individuals and organizations which spread misinformation and instill fear into the public for their own gain selfishly put countless people at risk," Lindenberger said in written testimony.
Measles was declared eliminated from the U.S. in 2000, thanks to high vaccination rates. The highly contagious, airborne disease has been revived, however, after false information linking the measles, mumps and rubella (MMR) to autism, linked to a false report in a U.K. publication.
The spread of social media has given rise to a growing anti-vaxxer movement in North America, with critics pointing to platforms like Facebook.
From Jan. 1 to Feb. 28 this year, 206 individual cases of measles have been confirmed in 11 states, according to the U.S. Centers for Disease Control and Prevention.
The new Facebook policy also follows a 3,200-word post by CEO Mark Zuckerberg on Wednesday in which he announced the company would pivot to a "privacy-focused" platform and would make changes in its News Feed and messaging features amid increasing scrutiny and investigations by regulators.
Facebook will reduce the ranking of groups and pages that spread misinformation about vaccines in News Feed and Search. It will also remove them from recommendations and predictions, reject ads with false information and eliminate targeting options, like “vaccine controversies,” Facebook's Vice President of Global Policy Management Monika Bickert wrote.
Likewise, Instagram Explore and hashtag pages won't show or recommend content with false information, Bickert said.
"We are exploring ways to share educational information about vaccines when people come across misinformation on this topic," she said.
Bickert said it would follow guidance from authorities such as the World Health Organization and the CDC, which have identified "verifiable vaccine hoaxes."
"For example, if a group or Page admin posts this vaccine misinformation, we will exclude the entire group or Page from recommendations, reduce these groups and Pages' distribution in News Feed and Search, and reject ads with this misinformation," Bickert wrote, adding that the company is "exploring ways to give people more accurate information."