Political Quarrel Overshadows Vaccination Advocacy: How the Vaccine Debate on Brazilian Twitter Was Framed by Anti-Vaxxers During Bolsonaro Government

Despite Brazil's tradition of successful mass immunization programs, the country has been experiencing alarming declines in vaccination coverage, especially among children. That is aggravated by the growth of anti-vaccine movements and the spread of health misinformation in social media in the last decade, which have worsened during the COVID-19 outbreak. Several reports link populism and far-right politicians to anti-vaccination support worldwide, which was also the case in Brazil during president Jair Bolsonaro's administration. This project aimed to identify the circulating pro and anti-vaccine narratives in Portuguese on Twitter, during a crucial decision-making period regarding childhood vaccination in Brazil, from December 9, 2021, until February 9, 2022. From the over one million tweets and four million retweets collected, we identified two well-defined groups, one in favor and another against vaccination. Within the large sample, we selected 1500 influencer tweets that received the highest impact (>500 retweets), in which we performed a content analysis. Although the pro-vaccine influencers received more retweets than anti-vaxxer ones, we observed that anti-vaccine movements successfully imposed the framework of discussions on Twitter. The subject of COVID-19 was the target of political polarization embedded in vital populist-like, anti-science and anti-traditional media discourses promoted by anti-vaxxers. As a counterpart, the pro-vaccine influencers reacted inarticulately, prioritizing criticizing the anti-vaccination actors, attitudes, and policies over promoting vaccines. A well-coordinated network of health communicators from science centers and health institutions, in partnership with properly briefed social media influencers and fact-checking sources, could more actively pre-tempt the public about vaccine misinformation and offer more credible sources in Portuguese.