Dynamics of communication on measles vaccination on digital platforms in the Brazilian context: challenges and perspectives.

The infodemic and the spread of disinformation have fostered mistrust in vaccines, health institutions, and governments, contributing to a global decline in vaccination coverage and the resurgence of vaccine-preventable diseases like measles. In recent years, the use of digital platforms to access health information, including vaccines, has increased significantly. However, the rapid dissemination of disinformation on these under-regulated platforms can greatly influence vaccination behavior. This study aimed to identify and analyze the main arguments used on Facebook® regarding measles vaccination. Posts and comments in Brazilian Portuguese were extracted using keywords such as "Measles Vaccines," "Triple Viral," and "Tetra Viral" from general and anti-vaccine pages from January 2017 to December 31, 2020. A sample from both datasets was selected and analyzed using deductive content analysis. Of the posts, 213 (84.5%) were classified as pro-vaccine, primarily promoting vaccination campaigns, with limited discussions on vaccine risk-benefit and collective responsibility. Notably, anti-vaccine pages, though fewer in number and followers, were more active in posting than pro-vaccine pages. Of the anti-vaccine posts, 118 (59.3%) focused on undermining vaccine safety and efficacy, spreading disinformation to downplay disease risks. Although pro-vaccine messages showed the highest engagement on the platform, more effective communication strategies are needed to complement traditional health systems, as anti-vaccine posts appear to influence vaccination behavior, particularly among hesitant communities.