Digital public health interventions at scale: The impact of social media advertising on beliefs and outcomes related to COVID vaccines

This paper analyzes whether social media advertising can be a cost-effective tool to influence attitudes and beliefs about COVID-19 vaccines and ultimately vaccinations. We conduct a meta-analysis of more than 800 experiments conducted by 174 public health-related organizations. Each experiment randomly assigned advertisements to a subset of users and measured the outcome, attitudes, and beliefs, through surveys. Although each experiment individually has too few subjects to reliably detect small effects, by pooling the data, we obtain more precise estimates of the overall average effect. The estimated average cost per additional influenced person, $3.41, and the estimated cost per additional vaccination, $5.68, can be compared to the social benefit when evaluating the cost-effectiveness of public health campaigns.