Content that spreads doubt about vaccines is easy to find online. | Patrick T. Fallon/AFP/Getty Images

Posts that discourage and make fun of Covid-19 vaccination are racking up engagement.

Social media companies like Facebook and YouTube have ramped up their policies against coronavirus misinformation and banned false claims about Covid-19 vaccines. But as distribution of the vaccines begin, online accounts are exploiting loopholes in new policies and successfully sharing misleading claims that attempt to discourage vaccination.

Throughout the pandemic, platforms have established and updated rules meant to curb false claims related to Covid-19. Between March and October, Facebook took down 12 million pieces of content on Facebook and Instagram, and it added fact-checking labels to another 167 million posts. But the rollout of an authorized Covid-19 vaccine has forced social media companies to adapt again, changing