In July, President Biden excoriated social media companies, accusing them of “killing people” by failing to regulate misinformation about the vaccines on their platforms. In August, Facebook released data that showed the most popular piece of content from January through March was a link to an article that cast doubt on the vaccine. Last Wednesday, attorneys generals from 14 states sent a letter to Mark Zuckerberg, Facebook’s chief executive, inquiring if the company provided special treatment to those disseminating vaccine falsehoods on the platform.