To study ways to reduce vaccine misinformation, Facebook researchers changed how posts are ranked for more than 6,000 users in the U.S., Mexico, Brazil, and the Philippines. Instead of seeing posts about vaccines that were chosen based on their popularity, these users saw posts selected for their trustworthiness.

The results were striking: a nearly 12% decrease in content that made claims debunked by fact-checkers and an 8% increase in content from authoritative public health organizations such as the WHO or U.S. Centers for Disease Control. Those users also had a 7% decrease in negative interactions on the site.