Virtual Ad-demic: Examining Skew in Facebook's Ad Delivery for Vaccine Information

Abstract

This study examines the narrative content, advertising strategies, and delivery patterns of vaccine-related advertisements on Facebook from 2018 to 2024, aiming to understand how these factors influence public perceptions of vaccination. Through an observational analysis of data sourced from Facebook's Ad Library, we explored the distribution and efficacy of pro-vaccine and anti-vaccine messaging across different demographics, and investigated potential biases introduced by Facebook's ad delivery algorithms. We annotated and analyzed 31,362 vaccine-related ads from 1,297 unique advertisers. By identifying key themes, assessing the distribution of impressions and spend, and examining the patterns of ad delivery across various genders, ages, and geographies, we use this comprehensive dataset to explore how ad themes correlate with spending trends and how effectively these messages are being delivered to targeted audiences. Our findings revealed that the distribution of ads often did not align with the intended demographic targets, suggesting underlying biases in Facebook's algorithm that could skew ad delivery based on gender and age. This study contributes to our understanding of the significant influence social media advertising holds over public health conversations and argues for increased transparency in algorithms to guarantee fair distribution of high quality information.