Since the start of the global COVID-19 pandemic, global authority figures, institutions, and the public have struggled to share accurate health information. As early as February 2020, the World Health Organization declared an infodemic, a glut of news pouring in and harming peoples’ ability to find trustworthy sources.1 Mis- and disinformation spread widely.i Social media companies, pressured and incentivized to curate the news, sought to surface accurate information about the pandemic, but faced a problem: What should they amplify in the absence of clear scientific consensus? As they pondered, anti-vaccine sentiments grew. Were the vaccines safe? Had our governments overstepped? Misinformation distorted answers to these questions. The global crisis created opportunities for governments, financially motivated actors, and conspiracy theorists to construct or amplify narrativesii that served their interests. The preexisting US anti-vaccine movementiii began to insert itself into the national conversation. As far back as January 2020, when talk of a COVID-19 vaccine was purely theoretical, anti-vaccine activists perceived an opportunity to undermine confidence in any and all vaccinations. As vaccinations rolled out in the US in late 2020, anti-vaccine activists became increasingly focused on undermining their uptake.