But, the notifications don't appear to completely prevent people from viewing anti-vaccination content. One screenshot the company shared with CNN shows that, at least on Instagram, individuals have the option to still see what other users have posted using a vaccine-related hashtag. This differs from Pinterest's recently announced approach, in which the company has said it will only display information from credible sources like the WHO. Additionally, unlike Pinterest, it doesn't appear Facebook has worked with the CDC and WHO to create content that lives directly on its platforms.

The new notifications are at least in part a reaction to a sudden surge in easily preventable diseases like the measles -- with more than 1,200 confirmed cases in the US since the start of the year. That's the most since 1992. Previously, Facebook had attempted to curb the spread of vaccine-related misinformation by downranking anti-vaxxer groups and pages. Of the big three social media platforms, the company is the last to start pointing users to more credible information on vaccines.